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浙江省宁波市鄞州区宁波市第七中学2020-2021学年七年级下学期期中考试科学试题卷及参考答案

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[首发]浙江省宁波市鄞州区七校2020-2021学年七年级下学期期中考试科学试题

[首发]浙江省宁波市鄞州区七校2020-2021学年七年级下学期期中考试科学试题

［首发］浙江省宁波市鄱州区七校【最新】七年级下学期期中考试科学试题学校:姓名：班级：考号：一、选择题1.在煤矿的矿井里，为防止爆炸事故，常采取的安全措施是（）A.戴呼吸面具B.准备好灭火器材C.通风并严禁烟火D.先做灯火试验，判断二氧化碳浓度2.以下不能说明大气中存在水的例子是（）A.夏天，蜡烛容易变软B.香脆的饼干放了几天后变软C.夏天打开冰箱门，有“白气”冒出D.夏天将冷饮倒入玻璃杯中，外壁可看到有水珠出现3.将等容积、等质量（包括瓶塞、导管、燃烧匙）的两集气瓶置于天平左右两盘，并调至平衡，然后分别放入等质量的白磷和木炭（如图）。

关闭弹簧夹a、b,使两者充分燃烧后，冷却至室温，此时打开弹簧夹a、b时观察到的现象是（）A.甲中进水B,乙中进水C.甲乙两者都进水D.甲乙两者都不进水4.将干冰放在空气中，其周围就会产生大量的白雾，因而舞台上常用其制造云雾缭绕的幻境，干冰能产生白雾是因为（）A.干冰升华出大量的水蒸气B.干冰升华出大量的白色二氧化碳气体C.干冰被空气中的氧气氧化产生了大量的白色气体D.干冰升华时吸收大量的热，使周围温度降低，大量的水蒸气凝结成了小液滴5.下列关于二氧化碳的用途只利用了其物理性质的是（）6.细心的小敏发现妈妈每次洗完头发后，总是用电吹风吹湿头发，而且还用梳子不停的抖动头发，这是为什么呢？（）A.梳子不停的抖动头发主要是为了增加水的表面积，加快水分蒸发B.梳子不停的抖动头发主要是为了提高水的温度，以加快水分蒸发C.梳子不停的抖动头发主要是为了减少水的表面积，加快水分蒸发D.用电吹风吹湿头发，主要是为了加快水分表面的空气流动，减慢水分蒸发7.黑暗的房间里点燃一蜡烛，在白墙和蜡烛之间放一块中间刺有方形小孔的硬纸，在白墙上的像是（）A.烛焰的影子B.方形的光斑C.烛焰倒立的像D.方形的烛焰像8.如图是一个一次性加热杯的示意图。

当水袋破裂时，水与固体碎块混合，杯内食物温度逐渐上升。

2022-2023学年浙江省宁波市鄞州区七年级(下)期中英语试卷及答案解析

2022-2023学年浙江省宁波市鄞州区七年级(下)期中英语试卷及答案解析

2022-2023学年浙江省宁波市鄞州区七年级（下）期中英语试卷一、完形填空（本大题共15小题，共15.0分）My name is Joe.I'm 13 years old.I study in a middle school.You want to know （1）______ I get to school，right？Well，I usually（2）______ home at about 7：00 a.m.and walk to the bus （3）______ .The school bus usually comes at 7：15 a.m.My school is（4）______ ，about 10 kilometers from my home.It （5）______ about 30 minutes to get there by bus.The bus ride is（6）______ boring because I always talk to my classmates.I have some friends.Do you want to know（7）______ hobbies？I like music very much.There are many（8）______ in my school and I want to join the Music Club.My friend Lisa is a girl and she likes （9）______ chess very much.She wants to join the Chess Club.Do you know Linda's hobby？Well，let me （10）______ you.Linda's favorite sport is jumping.（11）______ she doesn't want to join the Jumping Club.She wants to join the（12）______ Club.Why？Because she wants to be in the same club（13）______ me.David is（14）______ my friend.He likes English and he wants to join the English Club.He is（15）______ singing and he wants to join the Music Club ，too.1. A. how B. when C. what D. where2. A. get B. run C. go D. leave3. A. number B. ride C. stop D. bridge4. A. near B. far C. long D. short5. A. is B. takes C. draws D. makes6. A. always B. usually C. often D. never7. A. our B. my C. their D. her8. A. subjects B. games C. clubs D. jobs9. A. joining B. playing C. making D. working10. A. ask B. speak C. tell D. talk11. A. But B. Because C. And D. So12. A. Chess B. Jumping C. English D. Music13. A. to B. as C. for D. like14. A. too B. also C. either D. all15. A. good with B. good for C. good at D. good to二、阅读理解（本大题共15小题，共30.0分）AI'm Susie.I'm six years old.I will go to primary school in autumn.I'm lookingforward to（期待）it.I want to make new friends.I'm Jack.I'm in Grade One.I go to school by subway every day.When I'm inGrade Five，my mother will drive me to school.I'm Li Lei.I'm learning English.I will go to Australia to study in 2023.I willgo to Australia by plane.It will be my first time to take the plane.I'm Wendy.I'm 70 years old and I'm learning to use a computer，but it is noteasy.I will write emails and watch movies on the computer in three months.16. How will Jack go to school when he's in Grade Five？______A. By car.B. By bus.C. By bike.D. On foot.17. What will Wendy do in three months？______A. Use a telephone.B. Write emails.C. Play the piano.D. Play computer games.18. What can we learn from the form（表格）？______A. Jack likes making new friends.B. Susie will be a middle school student.C. Li Lei is looking forward to going to England.D. Wendy is not good at using a computer.BEason is a famous singer.He lives in a beautiful old house alone.The house has a long history—it's about 150 years old.From his big window，he can see the wonderful sea.Eason often gets up at about 9：30 in the morning.He only has some milk for breakfast.Then he sits on the sofa and plays the guitar.He plays it really well!There is a food store near Eason's house.For lunch，he goes there and buys hamburgers，juice and chicken.After lunch，he sings and writes songs.He admires （赞赏）singers in the 1970s，like Lou Reed and Leonard Cohen.He doesn't watch TV.He thinks watching TV is boring.In the evening，Eason goes out with his friends.They have dinner together and they always have a good time.19. What is NOT Eason's hobby？______A. watching TVB. singingC. playing the guitarD. writing songs20. After breakfast，Eason ______ .A. watches TVB. writes songsC. meet friendsD. plays the guitar21. What does Eason have for lunch______A. Noodles，milk and fishB. Noodles，juice and chickenC. Hamburgers，milk and fishD. Hamburgers，juice and chicken22. According to the passage，who is Leonard Cohen？______A. A singerB. A teacherC. Eason's friendD. Lou Reed's friendCMany people drive their cars to school or work now.So there are lots of cars on thestreets.Sometimes,it's not easy for you to get to school or work on time.Then youwant to take a plane to school or work.Can your dream come true？Yes!Four people in Germany（德国）make a new plane-Lilium Jet.It doesn't look like a plane but an egg.Many people think it looks funny.The nice "egg" can take two people and "run" about three hundred kilometers an hour.The Lilium Jet is not very big,as small as a car.So it doesn't need an airport（机场）.A small is OK.It can even take off（起飞）from a garden.Some people also call the Lilium Jet "a flying car".It's not difficult for you to learn to drive it.You can driveit like driving a car.Then is it safe to drive the "flying car"？Of course "Yes"!Some people has tested（测试）it for many times."It's really cool to see the Lilium Jet take to the sky.Everyone should have a try."says one of the makers.Maybe you can buy one next year if you like it.I'm sure your trip to school or work will be great.23. Sometimes,people can't get to school or work on time because ______ .A. they don't leave home earlyB. there are lots of cars on the streetsC. they don't like their schools or jobsD. they don't have their planes24. Which of the following is TRUE？______A. The Lilium Jet looks like a ball.B. It's not safe to drive the Liulium Jet.C. People can learn to drive the plane easily.D. The Lilium Jet needs an airport to take off.25. What is the best title（标题）for the passage？______A. Take a plane to schoolB. A new planeC. A flying carD. An egg26. The best structure（结构）of the passage may be ______ .A. ①→②③④→⑤B. ①②→③④→⑤C. ①→②③④⑤D. ①→②③→④⑤DDo you like telling stories about your life to others？Jessii Vee does.She tells her stories on theInternet，and lots of people like watching her videos.Jessii is from Ontario，Canada.She turns her life into her work."Every Sunday I think about what to film for my videos，"says Jessii."Then，on Monday，I wake up early to start making theually，a video takes just over an hour to make.I try to make five，so it takes most of my day.Then，from Tuesday to Friday，I edit（编辑）them."Sometimes when Jessii goes out，her fans recognize（认出）her."The other day I went to a coffee shop，"she says，"and one girl working there saw me.She was so excited.She left the shop to meet me outside to take pictures.It always makes me happy to see my fans are happy."▲Some people said that she has a big face and a really thin mouth.In the past，Jessii felt bad when people said those negative（负面的）things about her.But now she thinks differently."People were talking about things that I can't change.So I decided to love those things and I don't feel bad about myself now，"said Jessii.27. Jessii makes videos to ______ .A. find a jobB. ask for helpC. tell her storiesD. make more friends28. How many videos does Jessii try to make in a week？______A. Four.B. Five.C. Six.D. Seven.29. When the girl in the coffee shop saw Jessii，she was ______ .A. worriedB. afraidC. happyD. thankful30. We can put the sentence " ______ " into ▲.A. Online life isn't all good.B. Being safe online is very important.C. Jessii says making videos isn' t difficult.D. Jessii wants to be a big star on the Internet.三、任务型阅读-多任务混合（本大题共1小题，共5.0分）31. （1）______ .Harris has lunch at school.He likes eating fish，rice and vegetables very much.Because he doesn't want to be fat，he doesn't eat ice-cream or desserts after lunch.Instead，he has milk and some fruit.（2）______ .I don't like Tuesday.My lunch is from 12：00 to 13：00.Then I have history.After it，I have two Chinese classes for two hours.After class，we practice singing for the school art festival.School finishes at 5：00 p.m.So I have no time to play basketball with my friends after school. （3）______ .We have all our clothes at very good prices on November 11th.Everything is on a big sale.You can get sports shoes for ＄83.Do you like baseball hats？＄16 e to our store now and choose what you like.（4）______ .I'm a girl of 14.In my room，you can see my things in place.There's a clock，a lamp and a computer on my desk.And my model planes and toys are in the box near my desk.I put all my books in my bookcase.（5）______ .I have some interesting school activities in November.On the 13th，we have a soccergame.A book sale is on the 20th.And we have the art festival on November 27th.It is fun.My birthday is also on this day.This month is really busy for me.A.My Tidy RoomB.Volunteer DayC.Healthy School LunchD.A Busy NovemberE.A Busy AfternoonF.Big Sale Day(1)(2)(3)(4)(5)四、选词填空-短文（本大题共1小题，共5.0分）32.Elephants are smart（1）______ .They can （2）______ soccer or music.They can also draw very （3）______ .People say that "An elephant never （4）______ ".Elephants can walk for a long time and never get lost.They can also remember places with food and water.This helps（5）______ to live.(1)(2)(3)(4)(5)五、阅读填空（本大题共1小题，共10.0分）33. 阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

浙江省宁波市第七中学2023-2024学年七年级下学期期中数学试题

浙江省宁波市第七中学2023-2024学年七年级下学期期中数学试题

浙江省宁波市第七中学2023-2024学年七年级下学期期中数学试题学校:___________姓名：___________班级：___________考号：___________一、单选题1．一种细菌的长度约为0.0000018m，数据0.0000018用科学记数法表示为（）A．1.8×10−7B．1.8×10−6C．1.8×10−5D．−1.8×10−6 2．下列运算正确的是（）A．a2+a2=2a4B．a6÷a3=a2C．−2a3=−8a3D．a2×a5=a103．下列是二元一次方程的是（）A．x+2y=3B．x2+y=1C．1x+y=2D．2x−1=54．已知x=2y=−3是方程3x+ay=9的一个解，则a的值为（）A．−5B．−1C．1 D．5 5．下列图形中，由∠1=∠2，能得到AB∥CD的是（）A．B．C．D．6．已知x+y−2=0，则4x⋅22y的值是（）A．16 B．4 C．14D．8 7．已知x+y=3，xy=1，则(x−y)2的值为（）A．5 B．7 C．11 D．138．在解关于x、y的方程组ax+8y=7①3x−by=4②时甲看错①中的a，解得x=4，y=2，乙看错②中的b，解得x=−3，y=−1，则a和b的正确值应是（）A．a=−4.25，b=3B．a=4，b=13C．a=4，b=4D．a=−5，b=49．用如图1中的长方形和正方形纸板作侧面和底面，做成如图2的竖式和横式两种无盖纸盒．现在仓库里有500张正方形纸板和800张长方形纸板，问两种纸盒各做多少个，恰好将库存的纸板用完？设做竖式纸盒x个，横式纸盒y个，恰好将库存的纸板用完，则可列方程是（）A．x+2y=5004x+2y=800B．2x+2y=5004x+4y=800C．x+3y=5004x+2y=800 D．x+2y=5004x+3y=80010．把形状大小完全相同的小长方形卡片（如图1）按不同方式、不同数量、不重叠地放置于相同的大长方形中（如图2、图3），大长方形的一边长为8，其未被卡片覆盖的部分用阴影表示．已知图2和图3阴影部分的周长之比为6：7，则大长方形的周长为（）A．29 B．28 C．27 D．26二、填空题11．写一个解为x=3y=−2的二元一次方程．12．如图，如果∠2＝100°，那么∠1的同位角等于，∠1的内错角等于，∠1的同旁内角等于．13．计算(12m3−8m2+16m)÷(8m)=．14．如图，请你根据这一图形的面积关系写出一个等式：．15．如图，将一条两边沿互相平行的纸带折叠，设∠1=x°，则∠2=（用关于x的代数式表示）16．计算−32023×132024=．17．如图，已知AB∥CD，BE和DF分别平分∠ABF和∠CDE，若2∠E−∠F=51°，则∠CDE=．18．若关于x、y的方程组ax+2y=52x+3y=0有整数解，则正整数a的值为．三、解答题19．计算：(1)12−1+π−20240−−12024；(2)2a2b12ab−3ab2．20．解下列方程组：(1)2y−x=7x=3y−1；(2)2a+3b=163a−2b=11．21．先化简，再求值：a−b2−2a a+3b+a+2b a−2b，其中a=1，b=−3．22．△ABC的位置如图所示，将△ABC进行平移，使点A平移到点A′．请画出平移后的△A′B′C′．23．如图，已知∠1+∠2=180°，∠A=∠C．(1)AE与FC平行吗？请说明理由．(2)AD与BC的位置关系如何？为什么？24．因强降雨天气，有500名群众被困，某救援队前往救援，已知3艘小型船和2艘大型船一次可救援125名群众，1艘小型船和3艘大型船一次可救援135名群众．(1)每艘小型船和每艘大型船各能坐多少名群众？(2)若安排m艘小型船和n艘大型船，一次救援完，且恰好每艘船都坐满，请设计出所有的安排方案．25．将一副直角三角板按图1方式叠放在一起，并且直角顶点C重合，其中∠B=30°，∠D=45°．保持三角尺ABC固定不动，将三角尺CDE绕着点C顺时针旋转α度．探究以下问题：(1)如图2，当α=210°时，求证：AB∥EC；(2)当0°<α<180°时，若这两个三角尺的一组边互相平行，请画出相应的图形，并求出此时α的度数．四、填空题26．图1是一张足够长的纸条，其中PN∥QM，点A、B分别在PN、QM上，记∠ABM=α(0°<α< 90°)．如图2，将纸条折叠，使BM与BA重合，得折痕BR1，如图3，将纸条展开后再折叠，使BM与BR1重合，得折痕BR2，将纸条展开后继续折叠，使BM与BR2重合，得折痕BR3…依此类推，第n次折叠后，∠AR n N=（用含a和n的代数式表示）五、解答题27．已知6x=192，32y=192，求−2024x−1y−1−2的值．。

浙江省宁波市鄞州区2020学年七年级历史与社会下学期期中试题

浙江省宁波市鄞州区2020学年七年级历史与社会下学期期中试题

浙江省宁波市鄞州区2020学年七年级历史与社会下学期期中试题温馨提醒：闭卷，满分50分，考试时间60分钟。

请仔细审题，冷静思考，认真答题。

一、单项选择题（每题1分，25小题，共25分）1.我国是一个海陆兼备的国家，下列能证明这一特征的地理事实是（）A.幅员辽阔，国土面积居世界第三B.陆上边界漫长，与14个国家相邻C.陆地面积约960万平方千米，海域面积约300万平方千米D.东临四大海域，有大小岛屿数千个2.我国跨纬度最大和跨经度最广的省级行政单位分别是（）A.黑龙江省和内蒙古自治区B.海南省和内蒙古自治区C.黑龙江省和海南省D.新疆维吾尔自治区和内蒙古自治区3.我国人口分布极不平衡，其疏密的分界线大致是（）A.黑龙江漠河——云南省腾冲一线B.大兴安岭——阴山——贺兰山一线C.大兴安岭——太行山——雪峰山一线D.黑龙江黑河——云南省腾冲一线4.古人说“羌笛何须怨杨柳，春风不度玉门关”是指这里（）A.夏季风来得迟B.受夏季风影响非常小C.年降水量稀少D.雨季来得迟5.浙江地区夏季高温多雨，冬季温和少雨，雨热同期，其气候类型是（）A.温带海洋性气候B.温带季风气候C.亚热带季风气候D.热带季风气候6.下列选项符合台湾岛地理概况的是（）A.阿里山、日月潭是著名的旅游胜地B.基隆是台湾最大城市C.水果之乡，盛产苹果、香蕉和芒果等D.位于温带和亚热带季风区7.小明同学的居住地有一口井，每年有且只有一天有阳光直射井底的现象，他有可能住在下列哪个省份（）A.台、闽、粤、桂B.滇、黔、粤、闽C.云、桂、粤、台D.粤、闽、桂、滇8.我国现行的行政区划是（）A.省、县、乡B.省、地、县C.省、县、村D.省、市、县9.我国地势三级阶梯划分的依据主要是（）A.地形类型B.山脉走向C.平均海拔高度D.相对高度10.关于北方地区的叙述，正确的是（）A.位于我国地势第二阶梯上B.纬度较高，气候寒冷，不适宜发展农业C.长城以南的农作物一年一熟D.我国东部秦岭淮河以北的地区11.小兴安岭能成为我国重要的林业基地，其有利条件是（）①林区的交通极为便利②森林资源十分丰富③森林的破坏相当严重④冬季漫长而寒冷A.①②B.③④C.①③D.②④12.下列对黄土高原地形特征的描述，正确的是（）A.千沟万壑B.起伏平缓C.崎岖不平D.雪山连绵13.许多外国人喜欢游览北京的胡同，原因是（）A.胡同旅游消费的钱少B.北京胡同的环境好C.北京胡同有独特的历史文化D.北京胡同的交通便利14.开设青春期健康讲座（）A.可以帮助学生正确认识青春期的烦恼，使其快乐成长B.可以消除学生的一切心理烦恼C.可以帮助学生调节情绪，排解所有烦恼D.占用了学生的学习时间，得不偿失15.针对青春期出现“思维的批判性”，你认为正确的是（）A.它对青少年的成长全部都有利B.一定会成为我们前进的阻力C.是我们成长过程中不正常的心理现象D.是我们在学习中所需要的精神和勇气16.“青春让每个人都开一次花，但不担保每个人都结一次果。

2020-2021学年浙江省宁波市七年级语文下学期期中试题及答案

2020-2021学年浙江省宁波市七年级语文下学期期中试题及答案

浙江省七年级语文下学期期中试题考生须知：试卷共有五个大题，满分为120分，考试时间为120分钟。

一、书写（5分）本题根据卷面书写情况评分。

请你在答题时努力做到书写正确、工整。

二、积累运用（29分）1．读下面这段文字，根据拼音写出汉字。

（4分）读书，就像是隐身地串门。

我们通过阅读结识了为中国的国防武器事业鞠躬尽cu ì ⑴ 的邓稼先，l íng ⑵ 听了端木蕻良要为故土洗去污hu ì⑶ 和耻辱的誓言，体察了杨绛在迟暮之年对车夫老王真诚的愧 zu ò⑷ 之情……阅读让我们把生活中寂寞的辰光变成了享受。

2.古诗文名句默写。

（8分）○1士别三日，▲ 。

（《孙权劝学》）○2 ▲ ，惟解漫天作雪飞。

(韩愈《晚春》)○3家国情怀，是人类共有的一种朴素情感。

岑参《逢入京使》中“▲ ，▲ ”两句诗写出了思念家园的悲伤；《木兰诗》中“▲ ，▲ ”两句诗写出了木兰为报效国家，奔赴战场的飒爽英姿。

④“一砖一瓦皆是诗，一草一木总关情”。

晚年的王维看到盛开的芙蓉“花涧户寂无人，纷纷开且落”的落寞景象，不禁想起了自身的遭际，勾起了丝丝感伤之情。

但幸运的是苍翠的竹林给予了他心灵的慰藉，兴之所至，他可以 “▲ ，▲ ”（王维《竹里馆》），有琴声相伴的惬意生活又抚平了他心底的波澜。

3．文言积累。

（3分）○1见往事．．耳 ▲ ○2策勋．．十二转 ▲ ○3康肃忿然．．曰 ▲ 4.下列有关文学常识说法有误的一项是：( ▲ ) （3分）A ．《回忆鲁迅先生》作者是萧红，本文以女性特有的笔触，捕捉鲁迅先生日常生活中的一些琐事，刻画了一个很生活化的鲁迅形象。

B ．《卖油翁》的作者是南宋欧阳修，字永叔，号醉翁，晚号六一居士。

“唐宋八大家”之一。

本文选自他的《归田录》。

C.杨绛的丈夫是钱钟书，字默存，他的代表作是小说《围城》。

D ．《木兰诗》是南北朝时北方的一首民歌，文中出现的“可汗”为古代西北地区民族的最高统治者。

浙江省宁波市鄞州区2023-2024学年七年级下学期4月期中数学模拟试题(含答案)

浙江省宁波市鄞州区2023-2024学年七年级下学期4月期中数学模拟试题(含答案)

的延长线上，下列条件能判断AB C ．D ．34∠∠=12∠=∠D ∠金山银山不如绿水青山，某地准备购买一些松树苗和梭梭树苗绿化荒山，已知购买如图是一块长方形ABCD的场地，长AB＝102 m，宽AD＝中路宽都为1 m，两小路汇合处路宽为2 m，其余部分种植草坪，则草坪的面积为 m2.,24.（6分）我们规定：对于数对，如果满足，那么就称数对是“和积等(),a b a b ab +=(),a b 数对”：如果满足，那么就称数对是“差积等数对”，例如，a b ab -=(),a b 333322+=⨯．222233-=⨯所以数对为“和积等数对”，数对为“差积等数对”．3,32⎛⎫ ⎪⎝⎭22,3⎛⎫⎪⎝⎭(1)下列数对中，“和积等数对”的是；“差积等数对”的是_________(填序号)．①，②，③．2,23⎛⎫-- ⎪⎝⎭2,23⎛⎫- ⎪⎝⎭2,23⎛⎫- ⎪⎝⎭(2)若数对是“差积等数对”，求的值．()1,22x --x (3)是否存在非零有理数，，使数对是“和积等数对”，同时数对也m n ()2,m n ()2,n m 是“差积等数对”，若存在，求出，的值，若不存在，说明理由．m n 25.（8分）某公司后勤部准备去超市采购牛奶和咖啡若干箱，现有两种不同的购买方案，如下表：牛奶（箱咖啡（箱金额（元方案一20101100方案二3015__________(1)采购人员不慎将污渍弄到表格上，根据表中的数据，判断污渍盖住地方对应金额是 __元；(2)若后勤部购买牛奶25箱，咖啡20箱，则需支付金额1750元；①求牛奶与咖啡每箱分别为多少元？②超市中该款咖啡和牛奶有部分因保质期临近，进行打六折的促销活动，后勤部根据需要选择原价或打折的咖啡和牛奶，此次采购共花费了1200元，其中购买打折的牛奶箱数是所有牛奶、咖啡的总箱数的，则此次按原价采购的咖啡有箱．1426.（8分）用几个小的长方形、正方形拼成一个大的正方形，然后利用两种不同的方法计算这个大的正方形的面积，可以得到一个等式．例如：计算图1的面积，把图1看作一个大正方形，它的面积是；如果把图1看作是由2个长方形和2个小正方形组成的，它的面()2a b +积为，由此得到．222a ab b++()2222a b a ab b =++＋(1)如图2，由几个面积不等的小正方形和几个小长方形拼成一个边长为的正方形，()a b c ++从中你能发现什么结论？该结论用等式表示为________________________；(2)利用（1）中的结论解决以下问题：①已知，，求的值；10a b c ++=38ab ac bc ++=222a b c ++②如图3，由正方形边长为a ，正方形边长为b ，点在同一直线上，连接ABCD CEFG ,,D G C ，BD DF ，若，求图3中阴影部分的面积．23a b ab -==，E答案一、选择题（每小题3分，共30分）1.A2.D3. A4.C5. C6. D7. C8.D 9. B10. D二、填空题（每小题3分，共30分）11.12. x(x+y)(x-y) 13. -114. ±12 15. 201472yx -=16. 1 17. 0 18. 108° 19.. 4.5三、解答题（共40分）21.（6分））（1）计算：=-1+4+1 =4（2） 20232011()(3.14)2π--+-+-64x y =⎧⎨=⎩22. （6分）(1)∵，∴，∵，∴，∴；∥DE A C BED C ∠=∠AFD BED ∠=∠C AFD ∠=∠DF BC ∥(2) =60°FDE ∠23．（6分）（1）；3222x y x y -()22x y x y =-25=⨯10=（2）；()2332(2)(2)(2)a b a b ab a b a b +÷-+-2222142ab a a b =+-+22142ab b =+当，时，原式．1a =12b =2211114222⎛⎫⎛⎫=⨯⨯+⨯ ⎪ ⎪⎝⎭⎝⎭118=+98=24.（1）解：∵∴，()()()22242422,2,2,333333-+-=----=-⨯-=()()222233---=-⨯-∴是“差积等数对”；2,23⎛⎫-- ⎪⎝⎭∵∴，()()()2422242,22,2,333333+-=---=⨯-=-()()222233+-=⨯-∴是“和积等数对”；2,23⎛⎫- ⎪⎝⎭∵2422242,22,2,333333-+=--=--⨯=-∴既不是“和积等数对”，也不是“差积等数对”；故②；①2,23⎛⎫- ⎪⎝⎭（2）解：∵数对是“差积等数对”，∴，解得：；1,22x -⎛⎫- ⎪⎝⎭()112222x x ----=-⨯13x =-（3）解：存在，∵数对是“和积等数对”，同时数对也是“差积等数对”，()2,m n ()2,n m∴，∴，即，把代入得：2222m n mn n m mn +=⎧⎨-=⎩①②22m n n m +=-3n m =3n m =①，解得：，∴．即存在非零有理数，2323m m m m +=⨯56m =532n m ==56m =，使数对是“和积等数对”，同时数对也是“差积等数对”52n =()2,m n ()2,n m 25.（8分）（1）解：设牛奶一箱元，咖啡一箱元，x y 由题意得：，20101100x y +=（元），故1650；()3015 1.52010 1.511001650x y x y ∴+=+=⨯=（2）解：①设牛奶一箱元，咖啡一箱元，x y 由题意得：，解得：，2010110025201750x y x y +=⎧⎨+=⎩3050x y =⎧⎨=⎩答：牛奶与咖啡每箱分别为30元、50元；②设牛奶与咖啡总箱数为，则打折的牛奶箱数为箱，a 14a打折牛奶价格为：（元，打折咖啡价格为：（元），300.618⨯=500.630⨯=即打折咖啡价格与牛奶原价相同，设原价咖啡为箱，则打折咖啡与原价牛奶共有箱，b 13144a b a b ⎛⎫--=- ⎪⎝⎭由题意得：，13183050120044a a b b ⎛⎫⨯+⨯-+= ⎪⎝⎭整理得：，∴27201200a b +=12002727602020a ab -==-、均为正整数，∴是正整数，∴a 必须是20的倍数，a b 276020a-，或，，，，即此次按原价采购的咖啡有6箱，∴2033a b =⎧⎨=⎩406a b =⎧⎨=⎩a b > 40a ∴=6b =26.（8分）（1）图2中正方形的面积可以表示为：，()2a b c ++还可以表示为：，222222a b c ab ac bc +++++.∴，()2222222a b c a b c ab ac bc ++=+++++故()2222222a b c a b c ab ac bc++=+++++（2）①由（1）结论变形知：()2222222a b c a b c ab ac bc++=++---；1002ab ac bc =-++（）10076=-24=②ABCD DGF ABD FECGS S S S S =--- 阴影正方形1122AB AD FG DG AB AD EC CG =⋅-⋅-⋅-⋅()2221122a b a b a b =----221122a ab b =--()221122a b ab =--()()1122a b a b ab =+--∵且，∵，∴，∴23a b ab -==，()()224a b a b ab+=-+0a b +>4a b +=．115423222S ⨯⨯-⨯=阴影＝。

2022-2023学年浙江省宁波市鄞州区部分校七年级下学期期中语文试题

2022-2023学年浙江省宁波市鄞州区部分校七年级下学期期中语文试题

2022-2023学年浙江省宁波市鄞州区部分校七年级下学期期中语文试题1. 临摹汉字（要有书写的笔锋哦！）2. 欣赏字形：下图画面中是“___”四个字的变形，好有画面感！3. 辨析字义“授之以_____，不如授之以_____”（填“鱼”或“渔”）。

填写的依据是：前者比喻知识，后者比喻___________。

4. 巧接成语：四海为家——家_____晓——晓之以理——理_______5. 秒猜字谜例：需要一半，留下一半（打一字：雷）半推半就（打一字：）6. 读准字音：憎恶( )粗拙( )7. 飞花令飞花令又称“花间游”，是古代文人以“花”作诗为雅趣的游戏，流行于唐宋时期。

现在我们就以诵诗词来助雅兴。

（注意:本卷中出现的诗句不可用哦！）8. 词性判断“谁是最可爱的人”一句中“谁”“是”“最”“可爱”词性判断正确的一项（）A．副词动词形容词名词B．代词动词副词形容词C．代词副词形容词名词D．副词动词介词形容词9. 主持人带着大家开展“整本书阅读”系列活动，请按要求完成下面任务。

(1)为下面三位同学的读后感标题选择合适的书名（填写字母）。

标题：合作才能共赢——读_____》有感信仰显英雄本色——读《____》有感黑暗社会吞噬善良人性——读《____》有感书名：A.《骆驼祥子》 B.《红岩》 C.《创业史》 D.《水浒》(2)同学们针对《骆驼祥子》中的“洋车夫”展开话题讨论。

下面是甲乙同学的发言，请你结合．．小说具体内容．．．．．．，帮乙同学补充理由。

甲：作者在书中除了写祥子，还写了形形色色的洋车夫，最主要的目的就是让我们读者对老北京洋车夫这一行当留下深刻印象，从而体会到旧社会底层劳动者的悲苦生活。

乙：我认为不仅于此。

作者构思特别巧妙，还让我们在某些洋车夫，如老马，又如二强子身上，看到祥子最终的命运走向。

我说：我同意乙同学的看法。

如作者笔下的( )（老马和二强子二选一）10. 父亲的背高巧林①乡下老家的屋檐下，夕阳斜斜地照着。

2020-2021学年浙江省宁波市鄞州区七年级(下)期中数学试卷

2020-2021学年浙江省宁波市鄞州区七年级(下)期中数学试卷

2020-2021学年浙江省宁波市鄞州区七年级（下）期中数学试卷一、选择题（每小题3分，共30分）1．（3分）下列等式中成立的是（）A．a4•a＝a4B．a6÷a3＝a2C．（a3）2＝a5D．（ab2）3＝a3•b62．（3分）下列从左到右的变形属于因式分解的是（）A．（x+1）（x﹣1）＝x2﹣1B．m2﹣2m﹣3＝m（m﹣2）﹣3C．D．x2﹣5x+6＝（x﹣2）（x﹣3）3．（3分）据了解，新型冠状病毒（SARS﹣CoV﹣2）的最大直径大约是0.00000014米．数0.00000014用科学记数法表示为（）A．1.4×10﹣5B．1.4×10﹣6C．1.4×10﹣7D．14×10﹣7 4．（3分）将一直角三角板与两边平行的纸条如图所示放置，下列结论：（1）∠1＝∠2；（2）∠3＝∠4；（3）∠2+∠4＝90°；（4）∠4+∠5＝180°，其中正确的个数是（）A．1B．2C．3D．45．（3分）如果方程组的解为，那么被“★”“■”遮住的两个数分别是（）A．10，4B．4，10C．3，10D．10，36．（3分）一副三角板按如图方式摆放，且∠1比∠2大50°．若设∠1＝x°，∠2＝y°，则可得到的方程组为（）A．B．C．D．7．（3分）如图，已知AB∥DE，∠ABC＝70°，∠CDE＝140°，则∠BCD的值为（）A．20°B．30°C．40°D．70°8．（3分）从图1到图2的变化过程可以发现的代数结论是（）A．（a+b）（a﹣b）＝a2﹣b2B．a2﹣b2＝（a+b）（a﹣b）C．（a+b）2＝a2+2ab+b2D．a2+2ab+b2＝（a+b）29．（3分）方程（m2﹣9）x2+x﹣（m﹣3）y＝0是关于x，y的二元一次方程，则m的值为（）A．±3B．3C．﹣3D．910．（3分）有下列说法：①在同一平面内，过直线外一点有且只有一条直线与已知直线平行；②无论k取任何实数，多项式x2﹣ky2总能分解成两个一次因式积的形式；③若（t﹣3）3﹣2t＝1，则t可以取的值有3个；④关于x，y的方程组为，将此方程组的两个方程左右两边分别对应相加，得到一个新的方程，当a每取一个值时，就有一个确定的方程，而这些方程总有一个公共解，则这个公共解是．其中正确的说法是（）A．①④B．①③④C．②③D．①②二、填空题（每小题3分，共18分）11．（3分）因式分解：a2﹣2a＝．12．（3分）（﹣2021）0+（）﹣2+（﹣3）3＝．13．（3分）如图，在△ABC中，BC＝10cm，D是BC的中点，将△ABC沿BC向右平移得△A′DC′，则点A平移的距离AA′＝cm．14．（3分）如图，下列条件中：①∠BAD+∠ABC＝180°；②∠1＝∠2；③∠3＝∠4；④∠BAD＝∠BCD，能判定AD∥BC的是．15．（3分）4x2+（m﹣1）xy+9y2是完全平方式，则m＝．16．（3分）如图，直线l1⊥直线l2，垂足为O，Rt△ABC如图放置，过点B作BD∥AC交直线l2于点D，在△ABC内取一点E，连接AE，DE．（1）若∠CAE＝15°，∠EDB＝25°，则∠AED＝．（2）若∠EAC＝∠CAB，∠EDB＝∠ODB，则∠AED＝°．（用含n的代数式表示）三、解答题（有7题，共52分）17．（9分）（1）解方程：①；②．（2）简便计算：19.92+19.9×0.2+0.12．18．（5分）先化简，再求值：（2x+3）（2x﹣3）+（x﹣2）2﹣4x（x﹣1），其中x＝2．19．（5分）如图：在正方形网格中有一个△ABC，按要求进行下列作图（只借助于网格，需写出结论）：（1）过点A画出BC的平行线；（2）画出先将△ABC向右平移5格，再向上平移3格后的△DEF；20．（7分）（1）已知a+b＝5，ab＝，求下列各式的值：①a2+b2；②（a﹣b）2．（2）若2x+3y﹣4z+1＝0，求9x•27y÷81z的值．21．（8分）如图，已知∠A＝∠C，AD⊥BE，BC⊥BE，点E，D，C在同一条直线上．（1）判断AB与CD的位置关系，并说明理由．（2）若∠ABC＝120°，求∠BEC的度数．22．（8分）某电器超市销售每台进价为80元、200元的A，B两种型号的电风扇，如表所示是六月份前2周的销售情况：（进价、售价均保持不变，利润＝销售收入﹣进货成本）销售时段销售数量销售收入A种型号B种型号第一周652100元第二周4103400元（1）求A、B两种型号的电风扇的销售单价．（2）若超市一共采购这两种型号的电风扇共120台，售完后该超市能否实现利润为8000元的目标？若能，请给出相应的采购方案；若不能，请说明理由．23．（10分）我们通常用作差法比较代数式大小．例如：已知M＝2x+3，N＝2x+1，比较M 和N的大小．先求M﹣N，若M﹣N＞0，则M＞N；若M﹣N＜0，则M＜N；若M﹣N ＝0，则M＝N，反之亦成立．本题中因为M﹣N＝2x+3﹣（2x+1）＝2＞0，所以M＞N．（1）如图1是边长为a的正方形，将正方形一边不变，另一边增加4，得到如图2所示的新长方形，此长方形的面积为S1；将图1中正方形边长增加2得到如图3所示的新正方形，此正方形的面积为S2．用含a的代数式表示S1＝，S2＝（需要化简）．然后请用作差法比较S1与S2大小；（2）已知A＝2a2﹣6a+1，B＝a2﹣4a﹣1，请你用作差法比较A与B大小．（3）若M＝（a﹣4）2，N＝16﹣（a﹣6）2，且M＝N，求（a﹣4）（a﹣6）的值．2020-2021学年浙江省宁波市鄞州区七年级（下）期中数学试卷参考答案与试题解析一、选择题（每小题3分，共30分）1．（3分）下列等式中成立的是（）A．a4•a＝a4B．a6÷a3＝a2C．（a3）2＝a5D．（ab2）3＝a3•b6【分析】根据同底数幂的除法，底数不变指数相减；同底数幂的乘法，底数不变指数相加；幂的乘方，底数不变指数相乘；积的乘方等于乘方的积，对各选项计算后利用排除法求解．【解答】解：A、同底数幂的乘法底数不变指数相加，故A错误；B、同底数幂的除法底数不变指数相减，故B错误；C、幂的乘方底数不变指数相乘，故C错误；D、积的乘方等于乘方的积，故D正确；故选：D．2．（3分）下列从左到右的变形属于因式分解的是（）A．（x+1）（x﹣1）＝x2﹣1B．m2﹣2m﹣3＝m（m﹣2）﹣3C．D．x2﹣5x+6＝（x﹣2）（x﹣3）【分析】根据因式分解的定义逐个判断即可．【解答】解：A、从左到右的变形不属于因式分解，故本选项不符合题意；B、从左到右的变形不属于因式分解，故本选项不符合题意；C、从左到右的变形不属于因式分解，故本选项不符合题意；D、从左到右的变形属于因式分解，故本选项符合题意；故选：D．3．（3分）据了解，新型冠状病毒（SARS﹣CoV﹣2）的最大直径大约是0.00000014米．数0.00000014用科学记数法表示为（）A．1.4×10﹣5B．1.4×10﹣6C．1.4×10﹣7D．14×10﹣7【分析】绝对值小于1的正数也可以利用科学记数法表示，一般形式为a×10﹣n，与较大数的科学记数法不同的是其所使用的是负整数指数幂，指数n由原数左边起第一个不为零的数字前面的0的个数所决定．【解答】解：0.00000014＝1.4×10﹣7，故选：C．4．（3分）将一直角三角板与两边平行的纸条如图所示放置，下列结论：（1）∠1＝∠2；（2）∠3＝∠4；（3）∠2+∠4＝90°；（4）∠4+∠5＝180°，其中正确的个数是（）A．1B．2C．3D．4【分析】根据两直线平行同位角相等，内错角相等，同旁内角互补，及直角三角板的特殊性解答．【解答】解：∵纸条的两边平行，∴（1）∠1＝∠2（同位角）；（2）∠3＝∠4（内错角）；（4）∠4+∠5＝180°（同旁内角）均正确；又∵直角三角板与纸条下线相交的角为90°，∴（3）∠2+∠4＝90°，正确．故选：D．5．（3分）如果方程组的解为，那么被“★”“■”遮住的两个数分别是（）A．10，4B．4，10C．3，10D．10，3【分析】把代入2x+y＝16先求出■，再代入x+y求★．【解答】解：把代入2x+y＝16得12+■＝16，解得■＝4，再把代入x+y＝★得★＝6+4＝10，故选：A．6．（3分）一副三角板按如图方式摆放，且∠1比∠2大50°．若设∠1＝x°，∠2＝y°，则可得到的方程组为（）A．B．C．D．【分析】此题中的等量关系有：①三角板中最大的角是90度，从图中可看出∠1度数+∠2的度数+90°＝180°；②∠1比∠2大50°，则∠1的度数＝∠2的度数+50度．【解答】解：根据平角和直角定义，得方程x+y＝90；根据∠1比∠2的度数大50°，得方程x＝y+50．可列方程组为．故选：D．7．（3分）如图，已知AB∥DE，∠ABC＝70°，∠CDE＝140°，则∠BCD的值为（）A．20°B．30°C．40°D．70°【分析】延长ED交BC于F，根据平行线的性质求出∠MFC＝∠B＝70°，求出∠FDC ＝40°，根据三角形内角和性质代入求出即可．【解答】解：延长ED交BC于F，∵AB∥DE，∠ABC＝70°，∴∠MFC＝∠B＝70°，∴∠CFD＝110°，∵∠CDE＝140°，∴∠FDC＝180°﹣140°＝40°，∴∠C＝180°﹣∠CFD﹣∠CDF＝180°﹣110°﹣40°＝30°，故选：B．8．（3分）从图1到图2的变化过程可以发现的代数结论是（）A．（a+b）（a﹣b）＝a2﹣b2B．a2﹣b2＝（a+b）（a﹣b）C．（a+b）2＝a2+2ab+b2D．a2+2ab+b2＝（a+b）2【分析】根据面积的两种表示方法，即可解答．【解答】解：图1的面积为：（a+b）（a﹣b），图2的面积为：a2﹣b2，根据面积相等，可得：（a+b）（a﹣b）＝a2﹣b2．故选：A．9．（3分）方程（m2﹣9）x2+x﹣（m﹣3）y＝0是关于x，y的二元一次方程，则m的值为（）A．±3B．3C．﹣3D．9【分析】依据二元一次方程的定义列出关于m的不等式组求解即可．【解答】解：∵方程（m2﹣9）x2+x﹣（m﹣3）y＝0是关于x，y的二元一次方程，∴m2﹣9＝0，m﹣3≠0．解得：m＝﹣3．故选：C．10．（3分）有下列说法：①在同一平面内，过直线外一点有且只有一条直线与已知直线平行；②无论k取任何实数，多项式x2﹣ky2总能分解成两个一次因式积的形式；③若（t﹣3）3﹣2t＝1，则t可以取的值有3个；④关于x，y的方程组为，将此方程组的两个方程左右两边分别对应相加，得到一个新的方程，当a每取一个值时，就有一个确定的方程，而这些方程总有一个公共解，则这个公共解是．其中正确的说法是（）A．①④B．①③④C．②③D．①②【分析】利用平行公理对①判断，利用平方差公式的特点对②分析，③通过0指数、底数为1，底数为﹣1对代数式进行分类讨论得结果，④抓住a取每一个值方程的解都相同，求出x、y的值．【解答】解：①按照平行公理可判断在同一平面内，过直线外一点有且只有一条直线与已知直线平行，故本选项正确；②当k为负值时，多项式x2﹣ky2不能分解成两个一次因式积的形式，故本选项不正确；③当t＝4、时，（t﹣3）3﹣2t＝1，故本选项不正确；④新方程为（a﹣1）x+（a+2）y＝2a﹣5，∵a每取一个值时，就有一个方程，而这些方程总有一个公共解，∴当a＝1时，y＝﹣1，当a＝﹣2时，x＝3，∴公共解是．综上正确的说法是①④．故选：A．二、填空题（每小题3分，共18分）11．（3分）因式分解：a2﹣2a＝a（a﹣2）．【分析】先确定公因式是a，然后提取公因式即可．【解答】解：a2﹣2a＝a（a﹣2）．故答案为：a（a﹣2）．12．（3分）（﹣2021）0+（）﹣2+（﹣3）3＝﹣22．【分析】首先计算零指数幂、负整数指数幂、乘方，然后从左向右依次计算，求出算式的值是多少即可．【解答】解：（﹣2021）0+（）﹣2+（﹣3）3＝1+4﹣27＝﹣22．故答案为：﹣22．13．（3分）如图，在△ABC中，BC＝10cm，D是BC的中点，将△ABC沿BC向右平移得△A′DC′，则点A平移的距离AA′＝5cm．【分析】利用平移变换的性质解决问题即可．【解答】解：观察图象可知平移的距离＝AA′＝BD＝BC＝5（cm），故答案为5．14．（3分）如图，下列条件中：①∠BAD+∠ABC＝180°；②∠1＝∠2；③∠3＝∠4；④∠BAD＝∠BCD，能判定AD∥BC的是①②③．【分析】①由∠BAD+∠ABC＝180°，利用同旁内角互补得到AD∥BC，本选项符合题意；②由∠1＝∠2，利用内错角相等两直线平行得到AD∥BC，本选项符合题意；③由∠3＝∠4，利用内错角相等两直线平行得到AD∥BC，本选项符合题意；④由∠BAD＝∠BCD，不能判定出平行，本选项不合题意．【解答】解：①由∠∠BAD+∠ABC＝180°，得到AD∥BC，本选项符合题意；②由∠1＝∠2，得到AD∥BC，本选项符合题意；③由∠3＝∠4，得到AD∥BC，本选项符合题意；④由∠BAD＝∠BCD，不能判定出平行，本选项不合题意．故答案为：①②③．15．（3分）4x2+（m﹣1）xy+9y2是完全平方式，则m＝13或﹣11．【分析】先根据两平方项确定出这两个数，再根据完全平方公式的乘积二倍项即可确定m的值．【解答】解：∵4x2+（m﹣1）xy+9y2＝（2x）2+（m﹣1）xy+（3y）2，∴（m﹣1）xy＝±2×2x×3y，解得m﹣1＝±12，∴m＝13，m＝﹣11．故答案为：13或﹣11．16．（3分）如图，直线l1⊥直线l2，垂足为O，Rt△ABC如图放置，过点B作BD∥AC交直线l2于点D，在△ABC内取一点E，连接AE，DE．（1）若∠CAE＝15°，∠EDB＝25°，则∠AED＝40．（2）若∠EAC＝∠CAB，∠EDB＝∠ODB，则∠AED＝（）°．（用含n的代数式表示）【分析】（1）过点E作EF∥AC，利用平行线的性质解答即可；（2）根据平行线的性质和角的关系解答即可．【解答】解：（1）过点E作EF∥AC，∵AC∥EF，∵AC∥BD，∴AC∥EF∥BD，∴∠CAE＝∠AEF，∠EDB＝∠FED，∴∠AED＝∠AEF+∠FED＝∠CAE+∠EDB＝15°+25°＝40°；（2）∵AC∥BD，∴∠AGD＝∠ODB，∠CAO+∠AGD＝90°，∴∠CAB+∠ODB＝90°，∵∠EAC＝∠CAB，∠EDB＝∠ODB，由（1）同理可得：∠AED＝∠CAE+∠EDB＝（∠CAB+∠ODB）＝，故答案为：40°；（）．三、解答题（有7题，共52分）17．（9分）（1）解方程：①；②．（2）简便计算：19.92+19.9×0.2+0.12．【分析】依代入消元法，加减消元法可快速求解方程组．对于（2），联想到完全平方公式即可．【解答】（3+3+3分）解：（1）①解方程：，将①代入②得：x+2（2x﹣1）＝﹣7，解得x＝﹣1③．将x＝﹣1代入①得y＝﹣3．∴原方程组的解为．（1）②，解：将①×2得：4m+6n＝2③，②﹣③得：3m＝0，解得m＝0．将m＝0代入①得．∴原方程组的解为：．（2）简便计算：19.92+19.9×0.2+0.12．解：原式＝（19.9+0.1）2＝202＝400．18．（5分）先化简，再求值：（2x+3）（2x﹣3）+（x﹣2）2﹣4x（x﹣1），其中x＝2．【分析】根据整式的运算法则进行化简，然后将x的值代入原式即可求出答案．【解答】解：原式＝4x2﹣9+x2﹣4x+4﹣4x2+4x＝x2﹣5，当x＝2时，原式＝4﹣5＝﹣1．19．（5分）如图：在正方形网格中有一个△ABC，按要求进行下列作图（只借助于网格，需写出结论）：（1）过点A画出BC的平行线；（2）画出先将△ABC向右平移5格，再向上平移3格后的△DEF；【分析】（1）过点A连接一个小正方形的对角线，即可满足与BC平行．（2）根据网格结构找出点A、B、C平移后的对应点D、E、F的位置，然后顺次连接即可；【解答】解：（1）所作图形如下：直线l即满足与BC平行．（2）所画图形如下所示：．20．（7分）（1）已知a+b＝5，ab＝，求下列各式的值：①a2+b2；②（a﹣b）2．（2）若2x+3y﹣4z+1＝0，求9x•27y÷81z的值．【分析】（1）利用完全平方公式计算；（2）根据幂的乘方公式计算．【解答】解：（1）∵a+b＝5，ab＝﹣，①a2+b2＝（a+b）2﹣2ab＝52﹣2×（﹣）＝25+＝；②（a﹣b）2＝a+b）2﹣4ab＝52﹣4×（﹣）＝25+1＝26；（2）∵2x+3y﹣4z+1＝0，∴2x+3y﹣4z＝﹣1，∴9x•27y÷81z＝32x•33y÷34z＝32x+3y﹣4z＝3﹣1＝．21．（8分）如图，已知∠A＝∠C，AD⊥BE，BC⊥BE，点E，D，C在同一条直线上．（1）判断AB与CD的位置关系，并说明理由．（2）若∠ABC＝120°，求∠BEC的度数．【分析】（1）先根据AD⊥BE，BC⊥BE得出AD∥BC，故可得出∠ADE＝∠C，再由∠A ＝∠C得出∠ADE＝∠A，故可得出结论；（2）由AB∥CD得出∠C的度数，再由直角三角形的性质可得出结论．【解答】解：（1）AB∥CD．理由：∵AD⊥BE，BC⊥BE，∴AD∥BC，∴∠ADE＝∠C．∵∠A＝∠C，∴∠ADE＝∠A，∴AB∥CD；（2）∵AB∥CD，∠ABC＝120°，∴∠C＝180°﹣120°＝60°，∴∠BEC＝90°﹣60°＝30°．22．（8分）某电器超市销售每台进价为80元、200元的A，B两种型号的电风扇，如表所示是六月份前2周的销售情况：（进价、售价均保持不变，利润＝销售收入﹣进货成本）销售时段销售数量销售收入A种型号B种型号第一周652100元第二周4103400元（1）求A、B两种型号的电风扇的销售单价．（2）若超市一共采购这两种型号的电风扇共120台，售完后该超市能否实现利润为8000元的目标？若能，请给出相应的采购方案；若不能，请说明理由．【分析】（1）设A种型号的电风扇的销售单价为x元，B种型号的电风扇的销售单价为y 元，根据前两周的销售数量及销售收入，即可得出关于x，y的二元一次方程组，解之即可得出结论；（2）设采购A种型号的电风扇m台，B种型号的电风扇n台，根据该超市一共采购这两种型号的电风扇共120台且销售完毕后可获得8000元利润，即可得出关于m，n的二元一次方程组，解之即可得出结论．【解答】解：（1）设A种型号的电风扇的销售单价为x元，B种型号的电风扇的销售单价为y元，依题意，得：，解得：．答：A种型号的电风扇的销售单价为100元，B种型号的电风扇的销售单价为300元．（2）设采购A种型号的电风扇m台，B种型号的电风扇n台，依题意，得：，解得：．答：能实现利润为8000元的目标，可采购A种型号的电风扇50台，B种型号的电风扇70台．23．（10分）我们通常用作差法比较代数式大小．例如：已知M＝2x+3，N＝2x+1，比较M 和N的大小．先求M﹣N，若M﹣N＞0，则M＞N；若M﹣N＜0，则M＜N；若M﹣N ＝0，则M＝N，反之亦成立．本题中因为M﹣N＝2x+3﹣（2x+1）＝2＞0，所以M＞N．（1）如图1是边长为a的正方形，将正方形一边不变，另一边增加4，得到如图2所示的新长方形，此长方形的面积为S1；将图1中正方形边长增加2得到如图3所示的新正方形，此正方形的面积为S2．用含a的代数式表示S1＝a2+4a，S2＝a2+4a+4（需要化简）．然后请用作差法比较S1与S2大小；（2）已知A＝2a2﹣6a+1，B＝a2﹣4a﹣1，请你用作差法比较A与B大小．（3）若M＝（a﹣4）2，N＝16﹣（a﹣6）2，且M＝N，求（a﹣4）（a﹣6）的值．【分析】（1）根据题意分别表示出S1与S2，利用作差法比较大小即可；（2）利用作差法比较即可；（3）根据M＝N，得到所求即可．【解答】解：（1）根据题意得：S1＝a（a+4）＝a2+4a，S2＝（a+2）2＝a2+4a+4，∵S1﹣S2＝（a2+4a）﹣（a2+4a+4）＝a2+4a﹣a2﹣4a﹣4＝﹣4＜0，∴S1＜S2；故答案为：a2+4a，a2+4a+4；（2）∵A＝2a2﹣6a+1，B＝a2﹣4a﹣1，∴A﹣B＝2a2﹣6a+1﹣a2+4a+1＝a2﹣2a+2＝a2﹣2a+1+1＝（a﹣1）2+1≥1＞0，则A＞B；（3）由M＝N，得到M﹣N＝0，∴（a﹣4）2﹣16+（a﹣6）2＝0，整理得：a2﹣10a+18＝0，即a2﹣10a＝﹣18，则（a﹣4）（a﹣6）＝a2﹣10a+24＝﹣18+24＝6．。

2021-2022学年浙江省宁波七中教育集团七年级(下)期中数学试题及答案解析

2021-2022学年浙江省宁波七中教育集团七年级(下)期中数学试题及答案解析

2021-2022学年浙江省宁波七中教育集团七年级（下）期中数学试卷1. 2022年，中国举办第二十四届冬季奥林匹克运动会，如图，通过平移吉祥物“冰墩墩”可以得到的图形是( )A. B. C. D.2. 下列运算正确的是( )A. a3+a4=a7B. (−2a2)2=−2a4C. a5÷a2=a3D. a2⋅a3=a63. 下列各式中是二元一次方程的是( )A. 3x−6=x−1B. x=5yC. 2x−3y=x2D. 3x=2y4. 下列等式从左到右的变形，属于因式分解的是( )A. x2+2x−1=x(x+2)−1B. (a+b)(a−b)=a2−b2C. x2+4x+4=(x+2)2D. ax2−a=a(x2−1)5. 如图，已知直线a//b.直角三角板ABC的直角顶点C在直线b上，若∠1=50°，则∠2=( )A. 40°B. 60°C. 55°D. 50°6. 下列选项中，说法错误的是( )A. 在同一平面内，两条不相交的直线叫做平行线B. 两直线平行，同位角相等C. 垂直于同一条直线的两条直线互相平行D. 经过直线外一点，只能画出一条直线与已知直线平行7. 若关于x ，y 的二元一次方程组{x +y =5kx −y =9k 的解也是二元一次方程2x +3y =6的解，则k 的值为( )A. −34B. 34C. 43D. −438. 某家具生产厂生产桌椅，已知每块板材可做桌子1张或椅子3把，现计划用100块这种板材生产一批桌椅(不考虑板材的损耗)，设用x 块板材做桌子，用y 块板材做椅子，使得恰好配套(一张桌子两把椅子)，则下列方程组正确的是( )A. {x +y =100x =3yB. {x +y =1003x =yC. {x +y =1002x =3yD. {x +y =100x =6y9. 已知2a =5，16b =110，则(a +4b +1)3的值是( ) A. −1B. 0C. 12D. 110. 如图，有三张正方形纸片A ，B ，C ，它们的边长分别为a ，b ，c ，将三张纸片按图1，图2两种不同方式放置于同一长方形中，记图1中阴影部分周长为l 1，面积为S 1，图2中阴影部分周长为l 2，面积为S 2.若S 2−S 1=(l 1−l22)2，则b ：c 的值为( )A. 32B. 2C. 52D. 311. 目前世界上最小的开花结果植物是澳大利亚的出水浮萍，这种植物的果实像一个微小的无花果，质量只有0.000000076克，将数0.000000076用科学记数法表示为______．12. 因式分解：x 2−9=______．13. 如果(2x +m)(x −5)展开后的结果中不含x 的一次项，那么m =______． 14. 已知a +b =2，ab =1，则a 2b +ab 2的值为______．15. 如图，AB//CD ，BF 平分∠ABE ，DF 平分∠CDE ，∠ABF =50°，∠CDF =60°，则∠BED =______．16. 如果有一个角的两边和另一个角的两边分别平行，其中一个角为(x +10)°，两一个角为(2x −40)°，则这两个角的度数为______．17. (x +1)2x−1=1，则x =______．18. 二元一次方程组{ax +by =cmx +ny =p 的解为{x =1y =2，则{a(x +y)+2by =5cm(x +y)+2my =5p 的解为______．19. 计算：(1)−12015+(13)−2−(π−√2)0；(2)(2m 2+6m 2n −m 3)÷(−2m 2).20. 解下列方程组：(1){x =5−2y 3x −4y =5；(2){x −3(y −1)=3x 2+y−13=1．21. 先化简再求值：(3x +2)(3x −2)−5x(x −1)−(2x −1)2，其中x =19． 22. 如图，在所给的网格图(每个小格均为边长是1的正方形)中完成下列各题：(1)作出三角形ABC 向右平移4格，向下平移3格后所得的三角形A 1B 1C 1； (2)求出△ABC 的面积．23. 为了防治“新型冠状病毒”，我市某小区准备用3600元购买医用口罩和洗手液发放给本小区住户．若医用口罩买800个，洗手液买120瓶，则钱还剩余200元；若医用口罩买1200个，洗手液买80瓶，则钱恰好用完． (1)求医用口罩和洗手液的单价；(2)小王到药店购买小区同款医用口罩和洗手液，两样都买，共花了100元，有哪几种购买方案？24. 因为x 2+2x −3=(x +3)(x −1)，这说明多项式x 2+2x −3有一个因式为x −1，我们把x =1代入此多项式发现x =1能使多项式x 2+2x −3的值为0． 利用上述阅读材料求解：(1)若(x +3)是多项式x 2+kx +12的一个因式，求k 的值；(2)若(x −3)和(x −4)是多项式x 3+mx 2+12x +n 的两个因式，试求m ，n 的值． (3)在(2)的条件下，把多项式x 3+mx 2+12x +n 因式分解．25. 如图，已知AM//BN ，点P 是射线AM 上一动点(与点A 不重合)，BC 、BD 分别平分∠ABP和∠PBN ，分别交射线AM 于点C ，D ．(1)①当∠A=50°时，∠ABN的度数是______ ；②∵AM//BN，∴∠ACB=∠______ ；(2)当∠A=x°，求∠CBD的度数(用x的代数式表示)；(3)当点P运动时，∠ADB与∠APB的度数之比是否随点P的运动而发生变化？若不变化，请求出这个比值；若变化，请写出变化规律．(4)当点P运动到使∠ACB=∠ABD时，请直接写出2∠DBN+1∠A的度数．226. 已知x为自然数，且x+11与x−72都是一个自然数的平方，则x的值为______．27. 我们已经知道，利用图形面积可以解释代数恒等式的正确性．如完全平方公式可以用图1的面积表示．(1)根据图2写出一个代数恒等式______；(2)其实图形的面积也可以解释不等式的正确性．如已知正数a、b、c和m、n、l，并且满足a+m=b+n=c+l=k.试构造边长为k的正方形，利用其来说明al+bm+cn<k2的正确性．请你画出图形，并简单解释．答案和解析1.【答案】B【解析】【解析】解：根据平移的性质，通过平移吉祥物“冰墩墩”可以得到的图形是．故选：B．根据平移的性质进行判断．本题考查了平移的性质：平移前后两图形的形状和大小完全相同、各个部分的方向不会变．2.【答案】C【解析】解：A、a3+a4，无法计算，故此选项错误；B、(−2a2)2=4a4，故此选项错误；C、a5÷a2=a3，故此选项正确；D、a2⋅a3=a5，故此选项错误；故选：C．直接利用同底数幂的乘除运算法则以及积的乘方运算法则、合并同类项法则分别计算得出答案．此题主要考查了同底数幂的乘除运算以及积的乘方运算、合并同类项，正确掌握相关运算法则是解题关键．3.【答案】D【解析】解：A.是一元一次方程，故A不符合题意；B.不是整式方程，故B不合题意；C.含有两个未知数，但未知数x的最高次数是2，故C不符合题意；D.是二元一次方程，故D符合题意；故选：D．根据二元一次方程的定义求解即可．本题考查了二元一次方程的定义，注意二元一次方程必须符合以下三个条件：(1)方程中只含有2个未知数；(2)含未知数项的最高次数为一次；(3)方程是整式方程．4.【答案】C【解析】【分析】本题考查了因式分解的意义，解答本题的关键是掌握因式分解的意义即因式分解后右边是整式积的形式，且每一个因式都要分解彻底．根据因式分解的意义，把一个多项式化为几个整式的积的形式，这种变形叫做把这个多项式因式分解分别进行判断，即可得出答案．【解答】解：A、右边不是整式积的形式，不是因式分解，故本选项错误；B、右边不是整式积的形式，不是因式分解，故本选项错误；C、符合因式分解的定义，故本选项正确；D、右边分解不彻底，不是因式分解，故本选项错误；故选：C．5.【答案】A【解析】解：∵直线a//b，∠1=50°，∴∠3=50°，∵∠ACB=90°，∴∠2=∠ACB−∠3=90°−50°=40°．故选：A．根据平行线的性质求出∠3的度数，再根据∠2=∠ACB−∠3即可得出答案．此题考查了平行线的性质，熟练掌握平行线的性质，求出∠3的度数是解题的关键．6.【答案】C【解析】解：在同一平面内，两条不相交的直线叫做平行线，故A正确，不符合题意；两直线平行，同位角相等，故B正确，不符合题意；在同一平面内，垂直于同一条直线的两条直线互相平行，故C错误，符合题意；经过直线外一点，只能画出一条直线与已知直线平行，故D正确，不符合题意；故选：C．根据平行线的判定与性质、平行公理及推论求解判断即可．此题考查了平行线的判定与性质、平行公理及推论，熟记平行线的判定与性质、平行公理及推论是解题的关键．7.【答案】B【解析】解：{x+y=5k ①x−y=9k ②，①+②得：2x=14k，即x=7k，将x=7k代入①得：7k+y=5k，即y=−2k，将x=7k，y=−2k代入2x+3y=6得：14k−6k=6，解得：k=34．故选：B．将k看做已知数求出x与y，代入2x+3y=6中计算即可得到k的值．此题考查了二元一次方程组的解，以及二元一次方程的解，方程的解即为能使方程左右两边成立的未知数的值．8.【答案】C【解析】解：设用x块板材做桌子，用y块板材做椅子，∵用100块这种板材生产一批桌椅，∴x+y=100①，生产了x张桌子，3y把椅子，∵使得恰好配套，一张桌子两把椅子，∴2x=3y②，①和②联立得：{x +y =1002x =3y ， 故选：C ．设用x 块板材做桌子，用y 块板材做椅子，根据“用100块这种板材生产一批桌椅”，即可列出一个二元一次方程，根据“每块板材可做桌子1张或椅子3把，使得恰好配套，一张桌子两把椅子”，列出另一个二元一次方程，即可得到答案．本题考查了由实际问题抽象出二元一次方程组，正确找出等量关系，列出二元一次方程组是解题的关键．9.【答案】B【解析】解：∵2a =5，16b =110， ∴2a ×16b =5×110， ∴2a ×24b =12， ∴2a+4b =2−1， ∴a +4b =−1，∴(a +4b +1)3=(−1+1)3=0， 故选：B ．由2a =5，16b =110，得出a +4b =−1，代入(a +4b +1)3进行计算，即可得出答案．本题考查了幂的乘方与积的乘方，掌握幂的乘方与积的乘方的法则是解决问题的关键．10.【答案】D【解析】解：设大长方形的宽短边长为d ， ∴由图2知，d =b −c +a ，∴l 1=2(a +b +c)+(d −a)+(d −c)+(a −b)+(b −c)=2a +2b +2d ， S 1=d(a +b +c)−a 2−b 2−c 2，l 2=a +b +c +d +a +c +(a −b)+(b −c)=3a +b +c +d ， S 2=d(a +b +c)−a 2−b 2+bc ， ∴S 2−S 1=bc +c 2， l 1−l 2=b −c −a +d ，∴bc+c2=(b−c−a+d)2，2∴bc+c2=(b−c)2，∴3bc=b2，∴b=3c，∴b：c的值为3，故选：D．)2根据题目中的数据，设大长方形的宽短边长为d，表示出S2，S1，l1，l2，再代入S2−S1=(l1−l22即可求解．本题主要考查整式的混合运算，明确整式的混合运算的计算方法是解题的关键．11.【答案】7.6×10−8【解析】解：0.000000076=7.6×10−8．故答案为：7.6×10−8．绝对值小于1的正数也可以利用科学记数法表示，一般形式为a×10−n，与较大数的科学记数法不同的是其所使用的是负整数指数幂，指数由原数左边起第一个不为零的数字前面的0的个数所决定．本题考查用科学记数法表示较小的数，一般形式为a×10−n，其中1≤|a|<10，n为由原数左边起第一个不为零的数字前面的0的个数所决定．12.【答案】(x+3)(x−3)【解析】【分析】本题考查了因式分解−运用公式法，熟练掌握平方差公式是解本题的关键．原式利用平方差公式分解即可．【解答】解：原式=(x+3)(x−3)，故答案为：(x+3)(x−3)．13.【答案】10【解析】【分析】此题考查了多项式乘多项式有关知识，原式利用多项式乘以多项式法则计算，合并后根据结果不含x的一次项，即可确定出m的值．【解答】解：(2x+m)(x−5)=2x2−10x+mx−5m=2x2+(m−10)x−5m，∵结果中不含有x的一次项，∴m−10=0，解得m=10．故答案为10．14.【答案】2【解析】解：∵a+b=2，ab=1，∴a2b+ab2=ab(a+b)=2．故答案为：2所求式子提取公因式化为积的形式，将各自的值代入计算即可求出值．此题考查了因式分解的应用，将所求式子进行适当的变形是解本题的关键．15.【答案】140°【解析】解：过点E作直线ME//AB//CD，∵BF平分∠ABE，DF平分∠CDE，∴∠ABF=∠EBF，∠CDF=∠EDF，又∵ME//AB//CD，∴∠BEM+2∠ABF=180°，∠MED+2∠CDF=180°，∴∠BED=∠BEM+∠MED=180°−2×50°+180°−2×60°=140°，故答案为：140°．过点E作ME//AB//CD，根据角平分线及平行线的性质，可得∠BEM+2∠ABF=180°，∠MED+ 2∠CDF=180°，进而解答即可．本题考查了平行线的性质及角平分线的性质，用到的知识点为：两直线平行内错角相等，角平分线的性质，四边形的内角和为360°．16.【答案】60°和60°或80°和40°【解析】解：∵两个角的两边分别平行， ∴这两个角相等或互补，则x +10=2x −40或x +10+2x −40=180， 解得x =50或x =70，∴这两个角的度数分别为：60°和60°或80°和40°． 故答案为：60°和60°或80°和40°．由两个角的两边分别平行，可得这两个角相等或互补，据此列方程，解方程即可求得这两个角的度数．此题考查了平行线的性质．此题难度适中，解题的关键是注意由两个角的两边分别平行，可得这两个角相等或互补，注意分类讨论思想的应用．17.【答案】0或12【解析】解：根据任何不为0的零次幂都等于1可得，2x −1=0，解得x =12，而x =12时，x +1≠0，因此x =12符合题意；由1的任何次幂都等于1可得，x +1=1，解得x =0，因此x =0符合题意；由−1的偶次幂等于1可得x +1=−1，解得x =−2，当x =−2时，2x −1=−5不是偶数，因此x =−2不符合题意； 综上所述x =0或x =12， 故答案为：0或12．根据任何不为0的零次幂都等于1，1的任何次幂都等于1，−1的偶次幂等于1分别进行计算即可． 本题考查零指数幂以及有理数的乘方，理解“任何不为0的零次幂都等于1，1的任何次幂都等于1，−1的偶次幂等于1”是解决问题的关键．18.【答案】{x =0y =5【解析】解：我们将方程组{a(x +y)+2by =5c m(x +y)+2my =5p ，变形为{a(x+y)5+2by5=c m(x+y)5+2my 5=p，∵二元一次方程组{ax +by =cmx +ny =p的解为{x =1y =2，∴方程组{a(x+y)5+2by5=c m(x+y)5+2my 5=p ，有{x+y 5=12y 5=2，解方程组{x+y5=12y 5=2得{ x =0y =5，∴方程组{a(x +y)+2by =5c m(x +y)+2my =5p的解为{ x =0y =5．可以用整体法求解．我们将方程组{a(x +y)+2by =5c m(x +y)+2my =5p ，变形为{a(x+y)5+2by5=c m(x+y)5+2my 5=p，因为二元一次方程组{ax +by =cmx +ny =p的解为{x =1y =2，所以方程组{a(x+y)5+2by5=c m(x+y)5+2my 5=p ，有{x+y 5=12y 5=2，进而可求方程组{x+y5=12y 5=2的解，所得解即为方程组{a(x +y)+2by =5c m(x +y)+2my =5p 的解．本题考查学生对二元一次方程组的解的理解以及对方程整体法的应用，综合性比较强．19.【答案】解：(1)原式=−1+9−1=7．(2)原式=2m 2÷(−2m 2)+6m 2n ÷(−2m 2)−m 3÷(−2m 2) =−1−3n +12m.【解析】(1)根据乘方运算、负整数指数幂的意义、零指数幂的意义即可求出答案． (2)根据整式的除法运算即可求出答案．本题考查实数的运算以及整式的除法运算，解题的关键是熟练运用乘方运算、负整数指数幂的意义、零指数幂的意义以及整式的除法运算，本题属于基础题型．20.【答案】解：(1){x =5−2y①3x −4y =5②，把方程①代入②得，3(5−2y)−4y =5，解得y =65，把y =65代入方程①，得x =5−2×65，解得x =135， ∴原方程组的解为{x =65y =135；(2)整理，得{x =3y①3x +2y =8②，把方程①代入②得，3×3y +2y =8， 解得y =811，把y =811代入方程①，得x =3×811， 解得x =2411， ∴原方程组的解为{x =2411y =811．【解析】(1)运用代入法进行消元计算；(2)将方程x −3(y −1)=3变形为x =3y 后，再代入到第2个方程进行计算求解． 此题考查了二元一次方程组的求解能力，关键是能根据题目合理消元、求解．21.【答案】解：(3x +2)(3x −2)−5x(x −1)−(2x −1)2=9x 2−4−5x 2+5x −4x 2+4x −1 =9x −5，当x =19时，原式=9×19−5 =1−5 =−4．【解析】先去括号，再合并同类项，然后把x 的值代入化简后的式子进行计算即可解答． 本题考查了整式的混合运算−化简求值，准确熟练地进行计算是解题的关键．22.【答案】解：(1)如图，A 1B 1C 1即为所求；(2)△ABC 的面积=3×3−12×2×3−12×1×2−12×1×3=3.5． 【解析】(1)根据平移的性质即可作出三角形ABC 向右平移4格，向下平移3格后所得的三角形A 1B 1C 1；(2)根据网格利用割补法即可求出△ABC 的面积．本题考查了作图−平移变换，解决本题的关键是掌握平移的性质．23.【答案】解：(1)设医用口罩的单价为x 元，洗手液的单价为y 元，依题意得：{800x +120y =3600+2001200x +80y =3600，解得：{x =1.6y =21，答：医用口罩的单价为1.6元，洗手液的单价为21元． (2)设购买医用口罩m 个，洗手液n 瓶， ∵两样都买，共花了100元， ∴1.6m +21n =100， ∵m 、n 均为正整数， ∴{m =10n =4，∴只有一种购买方案，即购买医用口罩10个，洗手液4瓶．【解析】(1)设医用口罩的单价为x 元，洗手液的单价为y 元，根据“某单位准备用3600元购买医用口罩和洗手液．若医用口罩买800个，洗手液买120瓶，则还缺200元钱：若医用口罩买1200个，洗手液买80瓶，则钱恰好用完”，列出二元一次方程组，解之即可；(2)设购买医用口罩m 个，洗手液n 瓶，利用总价=单价×数量，可得出关于m ，n 的二元一次方程，结合“m ，n 均为正整数，即可得出答案．本题考查了二元一次方程组的应用以及二元一次方程的应用，解题的关键是：(1)找准等量关系，正确列出二元一次方程组；(2)找准等量关系，正确列出二元一次方程．24.【答案】解：(1)∵x −3是多项式x 2+kx +12的一个因式，∴x =3时，x 2+kx +12=0， ∴9+3k +12=0， ∴3k =−21， ∴k =−7， ∴k 的值为−7．(2)(x −3)和(x −4)是多项式x 3+mx 2+12x +n 的两个因式， ∴x =3和x =4时，x 3+mx 2+12x +n =0， ∴{27+9m +36+n =064+16m +48+n =0，解得{m =−7n =0，∴m 、n 的值分别为−7和0． (3)∵m =−7，n =0，∴x 3+mx 2+12x +n 可化为：x 3−7x 2+12x ， ∴x 3−7x 2+12x ， =x(x 2−7x +12) =x(x −3)(x −4)．【解析】(1)由已知条件可知，当x =3时，x 2+kx +12=0，将x 的值代入即可求得； (2)由题意可知，x =3和x =4时，x 3+mx 2+12x +n =0，由此得二元一次方程组，从而可求得m 和n 的值；(3)将(2)中m 和n 的值代入x 3+mx 2+12x +n ，提取公因式x ，则由题意知(x −3)和(x −4)也是所给多项式的因式，从而问题得解．本题考查了利用因式定理分解因式的特殊方法，根据阅读材料仿做，是解答本题的关键．25.【答案】130° CBN【解析】解：(1)①∵AM//BN ，∠A =50°， ∴∠A +∠ABN =180°，∴∠ABN=130°；②∵AM//BN，∴∠ACB=∠CBN；故答案为：130度，CBN；(2)∵AM//BN，∴∠ABN+∠A=180°，∴∠ABN=180°−x°，∴∠ABP+∠PBN=180°−x°，∵BC平分∠ABP，BD平分∠PBN，∴∠ABP=2∠CBP，∠PBN=2∠DBP，∴2∠CBP+2∠DBP=180°−x°，∴∠CBD=∠CBP+∠DBP=12(180°−x°)=90°−12x°；(3)不变，∠ADB：∠APB=1：2．∵AM//BN，∴∠APB=∠PBN，∠ADB=∠DBN，∵BD平分∠PBN，∴∠PBN=2∠DBN，∴∠APB：∠ADB=2：1∴∠ADB：∠APB=1：2；(4)∵AM//BN，∴∠ACB=∠CBN，当∠ACB=∠ABD时，则有∠CBN=∠ABD，∴∠ABC+∠CBD=∠CBD+∠DBN，∴∠ABC=∠DBN，∵BC平分∠ABP，BD平分∠PBN，∴∠ABP=2∠ABC，∠PBN=2∠DBN，∴∠ABP =∠PBN =2∠DBN =12∠ABN ， ∵AM//BN ，∴∠A +∠ABN =180°， ∴12∠A +12∠ABN =90°， 即12∠A +2∠DBN =90°．(1)由平行线的性质：两直线平行同旁内角互补和内错角相等可得；(2)由平行线的性质可得∠ABN =180°−x°，根据角平分线的定义知∠ABP =2∠CBP 、∠PBN =2∠DBP ，可得2∠CBP +2∠DBP =180°−x°，即∠CBD =∠CBP +∠DBP =90°−12x°； (3)由AM//BN 得∠APB =∠PBN 、∠ADB =∠DBN ，根据BD 平分∠PBN 知∠PBN =2∠DBN ，从而可得∠APB ：∠ADB =2：1；(4)由AM//BN 得∠ACB =∠CBN ，当∠ACB =∠ABD 时有∠CBN =∠ABD ，得∠ABC +∠CBD =∠CBD +∠DBN ，即∠ABC =∠DBN ，根据角平分线的定义可得∠ABP =∠PBN =12∠ABN =2∠DBN ，由平行线的性质可得12∠A +12∠ABN =90°，即可得出答案．本题主要考查平行线的性质和角平分线的定义，熟练掌握平行线的性质是解题的关键．26.【答案】1753【解析】解：∵x 为自然数，且x +11与x −72都是一个自然数的平方， ∴设a 2=x +11，b 2=x −72， ∵a 2−b 2=(a +b)(a −b)，∴(a +b)(a −b)=(x +11)−(x −72)， ∴(a +b)(a −b)=x +11−x +72， ∴(a +b)(a −b)=83， ∴{a +b =83a −b =1，解得：{a =42b =41，∵a 2=x +11，∴x =a 2−11 =422−11=1764−11=1753．故答案为：1753．设a2=x+11，b2=x−72，由平方差公式分解因式，结合x为自然数，可得(a+b)与(a−b)的值，解方程组可得a与b的值，从而由a2=x+11可解得x的值．本题考查了因式分解在实数求值中的应用，熟练掌握平方差公式及解二元一次方程组等知识点是解题的关键．27.【答案】2a2+3ab+b2=(2a+b)(a+b)【解析】解：(1)图2的面积为：2a2+3ab+b2=图1的面积为：(2a+b)(a+b)，∴可得：2a2+3ab+b2=(2a+b)(a+b)．(2)根据图形al+bm+cn是图中三个矩形的面积和．而k2是正方形的面积．大小关系显而易见．本题根据几何图形来进行代数恒等式的推导，要注意图形各部分面积和=整个图形的面积．利用几何图形推导代数恒等式，要注意几何图形整体面积与各部分面积的关系．。

2020-2021学年宁波第七中学高三英语下学期期中考试试卷及答案

2020-2021学年宁波第七中学高三英语下学期期中考试试卷及答案

2020-2021学年宁波第七中学高三英语下学期期中考试试卷及答案第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项ASome of the world’s most talented musicians have played concerts atLincolnCenter. On September 10, the center hosted a unique class of star musicians: kids and teens. The young players are part of the World Peace Orchestra, or WPO. The group held its first Music for Peace concert inNew York City, with 134 students from more than 60 countries taking part. Musicians were chosen from all over the world.The World Peace Orchestra began in 2013. The nonprofit group brings kids together using the common language of music. To be considered for the orchestra, students first had to be recommended by their teachers and then audition online for a group of judges. Once chosen, professional musicians and teachers then worked with the players to improve their skills.Some of the young musicians played classical instruments, such as violins and flutes. Others played instruments unique to their home country. For example, Amold Mugo, 16, fromKenya, played an instrument called the djembe. The drum is originally fromWest Africa. Mugo said he was shocked when he learned he was chosen for the orchestra. “I can’t express how I felt. I was rolling on the floor. It’s a once in a lifetime opportunity,” he said.Adomas Hendrixson, 13, fromLithuania, played piano for the WPO. Before theNew York Cityperformance, Hendrixson talked about what he hoped to take away from the event. “Fun and joy-- people smiling and clapping,” he said.“This is one of the only times in your life this could happen and I'm very excited.”Mugo says his favorite part of the WPO is making new friends from around the world. “I hope when I go home, I just take a little bit of every friend that I made here-- Brazil, Portugal, Queens,” Mugo said, “I hope that I take part of their culture home with me so I understand them more.”1. Who is most likely to have played for the WPO according to this passage?A. Li Ming, 16, a student fromChina.B. Daniel, 44, a judge fromAmerica.C. Edward, 21, a clerk fromAustralia.D. Catherine, 32, a teacher fromEngland.2. We can learn from the last paragraph that Mugo ________.A.performed best for the WPO.B. has learned some foreign culture.C. was eager to be chosen for a second time.D. received a great award for his performance.3. What would be the best title for this passage?A. Kids were good at playing music.B. Mugo liked making foreign friends.C. Concerts were played atLincolncentre.D. Young musicians played for peace.BEach year, the women of Olney and Liberal compete in an unusual footrace. Dressed in aprons (围裙) and headscarves, they wait at both towns’starting lines. Each woman holds a frying pan with one pancake inside. At the signal, the women flip (轻抛) pancakes and they’re off!This “pancake racing” tradition is said to have started on Shrove Tuesday, 1445, in Olney. Shrove Tuesday is the day beforethe Christian season of Lent (大斋戒) begins. During Lent, many people decide to give up sugary or fatty foods.Legend says that in 1445, an Olney woman was making pancakes to use up some of her sugar and cooking fats before Lent. She lost track of time and suddenly heard the church bells ring, signaling the beginning of the Shrove Tuesday service. Realizing that she was going to be late for church, she raced out the door still wearing her apron and headscarf and holding her frying pan with a pancake in it. In the following years, the woman’s neighbors imitated her dash to church, and pancake racing was born.The rules are simple. Racers must wear the traditional headscarf and apron. They must flip their pancakes twice - once before starting and once after crossing the finish line. After the race, there are Shrove Tuesday church services. Then Liberal and Olney connect through a video call to compare race times and declare a winner.In both towns, the races have grown into larger festivals. Olney’s festival is an all-day event starting with a big pancake breakfast. Liberal’s festival lasts four days and includes a parade, a talent show, and contests that feature eating and flipping pancakes. Although the women’s race is still the main event, both towns now hold additional races for boys and girls of all ages.4. How did pancake racing start?A. A woman in Olney created it.B. Women made pancakes before Lent.C. A woman dashed to church with a pancake.D. People followed the suit of an interesting incident.5. What should racers obey during the race?A. They can wear fashionable headscarves and aprons.B. They must flip their pancakes once in the race.C. They must flip their pancakes at the beginning of the race.D. They can flip their pancakes in the middle of the race.6. What can we learn about the race from the last paragraph?A. People can show their talent in Olney festival.B. People can enjoy a one-day holiday in Liberal.C. The race is not only intended for women now.D. People can have a big pancake breakfast in both towns.7. What is the text mainly about?A. The origin of pancake racing.B. The history of pancake racing.C. The development of pancake racing.D. The introduction to pancake racing.CThere is no such thing as a “safe" level of drinking, with increased consumption of alcohol associated with poorer brain health, according to a new study.In an observational study, which has not yet been peer-reviewed, researchers from the University of Oxford studied the relationship between the self-reported alcohol intake of some 25,000 people in the UK, and their brain scans. The researchers noted that drinking had an effect on the brain's gray matter-regions in the brain that make up "important bits where information is processed," according to leadauthor Anya Topiwala, a senior clinical researcher at Oxford.“The more people drank, the less the volume of their gray matter,“ Topiwala said via email. "Brain volume reduces with age and more severely with dementia(痴呆症).Smaller brain volume also predicts worse performance on memory testing,“ she explained. "While alcohol only made a small contribution to this(0. 8%), it was a greater contribution than other "modifiable" risk factors," she said, explaining that modifiable risk factors are “ ones you can do something about, in contrast to aging.”The team also investigated whether certain drinking patterns, beverage types and other health conditions made a difference to the impact of alcohol on brain health. They found that there was no "safe" level of drinking-meaning that consuming any amount of alcohol was worse than not drinking it. They also found no evidence that the type of drink— such as wine, spirits or beer—affected the harm done to the brain. However, certain characteristics, such as high blood pressure, obesity or binge-drinking, could put people at higher risk, researchers added.The risks of alcohol have long been known：Previous studies have found that there's no amount of liquor, wine or beer that is safe for your overall health. Alcohol was the leading risk factor for disease and premature death in men and women between the ages of 15 and 49 worldwide in 2016, accounting for nearly one in 10 deaths, according to a study published in The Lancet in 2018.“It has been known for decades that heavy drinking is bad for brain health," Sadie Boniface, head of research at the UK's Institute of Alcohol Studies, said via email. "We also shouldn't forget alcohol affects all parts of the body and there are multiple health risks. ”8. What is the function of gray matter?A. Control the mount of alcoholB. Process informationC. Scan the brainD. Predict the performance on memory9. Which is NOT true in the following statements according to the study?A. Drinking alcohol is worse than not drinking.B. With people getting older, brain volume reduces.C. Alcohol was the major risk factor for disease and premature death.D. The less people drink alcohol, the more the volume of their gray matter.10. Which is one of the "modifiable" risk factors?A. SmokingB. AgingC. DeathD. Disease11. What is the main idea of the text?A. The mount of alcohol is not related to people's health.B. People drinking alcohol do harm to their brain health.C. People drinking alcohol lead to dementia.D. Theresa great deal of liquor, wine or beer that is safe for health.DI have a memory of being about five years old, picking up a beautiful grilled(烧烤的）cheese sandwich madefor me by my hard —working mother and turning it over to see that theother side was burned. Suddenly what I thought was the perfect sandwich was not so perfect. Mom had tried to hide that fact from me. There was no question; I ate it anyway without complaining. However, that moment has stuck in my mind for many years. Now, at the age of 43 as a mother of two children and as a biology professor where I am routinely the "academic mother" of hundreds of students every year,I find that I believe inThe Grilled Cheese Principle.Here is what I mean Making a grilled cheese sandwich is easy right? But when I think of how many burned grilled cheese sandwiches I have eaten, or I have made myself, I realize that most of the grilled cheese sandwiches I have known have had at least one burned side. The thing is that although it is a ly easy thing to make, I can also easily lose focus, and before long the sandwich is burned. For my mother, the first side was usually perfect and the second side got burned due to her being distracted. For me,I have tended to burn the first side,but then I more carefully monitor the second side.Either way,the grilled cheese sandwich suffers because it has not been given the attention it deservesSo, I have learned that even the simplest task deserves my full attention. When I am multi-tasking, I am doing none of the tasks well. And when I allow myself to be distracted, I am not in the present moment — not paying attention to the small details of living or enjoying the processSo now, I believe the best way to make a perfect grilled cheese sandwich is to make only one at a time and give it my full attention.12. How did the writer react to the sandwich with burned side?A. She ate it with some complaintsB. She showed no interest.C. She thought it was still perfectD. She was deeply impressed with it13. What doesThe Grilled Cheese Principlemean?A. Even simple things deserve full attentionB. Losing focus makes the sandwich burnedC. Self-made sandwiches are always burnedD. we should make only one sandwich at a time14. Which of the following can we infer from the passage?A. Everything cannot be done well without full attentionB. Moms always like to lie to kids when they have done something wrongC. We can lose focus more easily when we do easy things.D. Multi-tasking can be an obstacle to the achievement of tasks.15. What does the writer mainly want to tell us?A. Nothing is perfectB. Learn to appreciate the burned sandwichesC. Devote yourself to one thing at a time.D. Never do multi-tasks第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

浙江省宁波市鄞州区宁波大学附属学校2021-2022学年七年级下学期期中数学试题

浙江省宁波市鄞州区宁波大学附属学校2021-2022学年七年级下学期期中数学试题

浙江省宁波市鄞州区宁波大学附属学校2021-2022学年七年级下学期期中数学试题学校:___________姓名：___________班级：___________考号：___________A．电梯的升降B．夏天电风扇中运动的扇叶C．汽车挡风玻璃上运动的刮雨器D．跳绳时摇动的绳子只燕重y 两，下列方程组中正确的是（ ）A ．455616x y y x x y +=+⎧⎨+=⎩B ．455610y x x y x y +=+⎧⎨+=⎩C ．455610x y y x x y +=+⎧⎨+=⎩D ．455616y x x y x y +=+⎧⎨+=⎩ 10．如果一个正整数可以表示为两个连续奇数的平方差，那么称该正整数为“和谐数”．如22831=-，221653=-，即8，16均为“和谐数”．在不超过2022的正整数中，所有“和谐数”之和等于（ ）A ．255054B ．255064C ．250554D ．255024二、填空题18．已知方程组111222a x b y c a x b y c +=⎧⎨+=⎩的解是34x y =⎧⎨=⎩，则方程组()()()()1112223121431214a x b y c a x b y c ⎧+--=⎪⎨+--=⎪⎩的解是________．三、解答题数式的值因x 的取值不同而变化．探究二：把代数式x 2+2x +5进行变形，如：x 2+2x +5＝x 2+2x +l +4＝（x +1）2+4，可以看出代数式x 2+2x +的最小值为 ，这时相应的x ＝ ．根据上述探究，请解答：（1）求代数式﹣x 2﹣8x +17的最大值，并写出相应x 的值．（2）把（1）中代数式记为A ，代数式9y 2+12y +37记为B ，是否存在，x ，y 的值，使得A 与B 的值相等？若能，请求出此时x •y 的值，若不能，请说明理由．四、填空题五、解答题29．将7张相同的小长方形纸片（如图1所示）按图2所示的方式不重叠的放在长方形ABCD 内，未被覆盖的部分恰好被分割为两个长方形，面积分别为1S 和2S ．已知小长方形纸片的长为a ，宽为b ，且a b >．(1)当9a =，3b =，30AD =时，长方形ABCD 的面积是______，12S S -的值为______；MPN ∠。

2020-2021学年宁波市第七中学高三英语期中考试试题及答案解析

2020-2021学年宁波市第七中学高三英语期中考试试题及答案解析

2020-2021学年宁波市第七中学高三英语期中考试试题及答案解析第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项AJuanito Estrella has been a housekeeping manager on the US-based large passenger ship Carnival Spirit for 18 months and feels he has found the suitable position in his career(职业). He has always wanted to travel. “I guess I am a really restless spirit.I like traveling, so when the chance came, I jumped at it,” he says.The chance came in the form of a newspaper advertisement for work on cruise ships（游船）. At the time Estrella was the housekeeping manager at a Melbourne hotel. He applied and, after two interviews, a medical check and police clearance, the job was his.Estrella is responsible(负责的)for the cleanliness of the ship, making sure that 160 crew work properly. “I enjoy it because there is no other work-you wake up each day in a different place anda different culture. It’s exciting when you go to the next country and you don’t understand the language,” he says.Estrella likes being busy and getting to know people from all over the world. The 1,000 crew come from 94 countries, and Estrella has learnt Spanish and a little Croatian.But there is adownside. “You cannot get really drunk...because you have safety responsibilities to yourself and others,” he says. “You don’t really think about home.You start to think about home only when you get closer to your vacation and wonder what you’ll be doing.”Life on the ship is anything but cruising. Estrella and his fellows work at least 10 hours a day, seven days a week. He warns the job is not for everybody. “You have to love being busy and be prepared to work every day-and to give up drinking too much alcohol.” In his spare time, if the ship sails into a port, Estrella explores it, otherwise he works out in the crew’s gym, goes on the internet or calls home.1.Which of the following is true?A.He has been a housekeeping manager for 18 months.B.He doesn’t drink wine now.C.He cannot speak a foreign language.D.He used to be a housekeeping manager.2.The underlined word“downside”in paragraph 5 probably means ________ .A.disappointmentB.disadvantageC.failureD.loss3.In the last paragraph, the writer thinks that life on the ship is ________.A.not a tiring journey at allB.just an interesting voyageC.far from a voyage for pleasureD.more than a pleasant travel by seaBIf you believe in thermometers (温度计), you should believe in global warming. And if you believe in eating French fries with your hamburger, you should worry more about carbonemission.It won't happen overnight, but as the planet’s climate changes, the growth cycles of main crops will all be heavily affected. Here are three of the crops that might not beat the heat.The potato actually needs a great deal of beauty rest to develop properly. “They need a cool nighttime temperature in order to start growing the tuber, the part that we eat,” Nelson says.Temperature and altitude are two primary concerns in coffee growth, and farmers are stuck between a rock and a hard place. “We know that coffee grows in a certain temperature range,” Nelson says. “They've been moving up the mountains, but at some point you run out of mountains to move up.” Higher-grade strains of Arabica coffee in Central American regions are at particular risk due to the need for lower growing temperature, especially since diseases and pests are also becoming more of a factor as temperatures rise.Even if you're looking at the direct effects of temperature alone, rice is in trouble. “As nighttime temperatures go up, the rice is going to have a problem flowering and won't make as many seeds,” Nelson says. In addition to this direct heat consequence, rising sea levels will flood many rice paddies and destroy water salinity levels, while droughts will lower production, raise prices, and further shame westerners who are clumsy with chopsticks to be able to clear their plates once a new grain is adopted.4. What is the closest meaning to the underlined word “emission” in Paragraph 1?A. Mixture.B. Pollution.C. Giving off.D. Going down.5. What does the potatoes' development need according to Nelson?A. Cool temperature at night.B. Sudden rise of the temperature.C. Enough water and salt.D. Much sunshine and fresh air.6. The rice is difficult to flower,probably because ________.A. sea levels go up suddenlyB. many seeds can't be producedC. the temperature rises at nightD. both temperature and altitude rise7. What is the best title for the text?A. How Does Global Warming Affect WesternersB. How Does the Cool Temperature Affect RiceC. What Is the Real Reason For Crops’ GrowthD. Three Crops That Won't Survive Climate ChangesCWhere doyou usually put your toothbrush?Do you keep it in the bathroom? How’s your toothbrush looking these days? Even if you can’t see it with a naked eye, experts say it may be saturated(使饱和)with millions of toilet germs!Dr. Charles Oerba, a germ expert, is amicrobiology professor at the University of Arizona. He says there are approximately 3 million bacteria per square inch in most toilet bowls, and every time you flush it without closing the lid, those millions of bacteria droplets spray into the air as far as twenty feet away and dirty everything in their path. And a common victim is your poor toothbrush, usually, left out on the bathroom sink, right?So, what do we do? Dr. Gerba says it’s easy. Close the toilet lid before you flush—that’ll greatly cut downthe germs, which will otherwise float in the air. And wash your toothbrush every few days in mouthwash or peroxide to get rid of any germs hiding in it. You can even put it through the dishwasher to sanitize(消毒)it. And always store your toothbrush in a closed cabinet.Here’s one more tip from Dr. Gerba, who says our kitchen sink is probably dirtier than our toilet. “If an alien came from space and studied the bacterial counts, he probably would conclude he should wash his hands in your toilet and go to the bathroom in your sink.” He says that’s because the kitchen sink is a great place where E. coli(大肠杆菌)to live and grow since it’s wet and damp. Bacteria feed on the food that people put down the drain or—that’s left on dishes in the sink. To reset your sink’s bacteria count back to zero, you’d better regularly wash it with hot water and sanitize yoursink with special chemicals. In fact, you may want to do it every day or before preparing dinner.8. What is the purpose of the text?A. To show how to brush your teeth.B. To tell people the importance of health.C. To warn people of the invisible germs.D. To introduce a microbiology professor.9. What can we learn from Paragraph 2?A. Bathroom sinks are the dirtiest places.B. Bacteria are bad for people’s health.C. Why bacteria spread through the air.D. How bacteria spread in the bathroom.10. What does the underlined word“that”in Paragraph 4 refer to?A. The food.B. The toothbrush.C. The sink.D. The chemical.11. Why does Dr. Gerba mention the example of an alien?A. To tell us a fiction story of an alien studying bacteria.B. To show our kitchen sink may be dirtier than our toilet.C. To teach us how to reset sink’s bacteria count back to zero.D. To prove coli prefers to live in the kitchen and the drain.DIt was very cold and I had been watching a homeless man make himself comfortable in a “shelter” on the river bank. His “shelter” was a tarpaulin (油布)tied to rocks to keep the wind from blowing it away. He had been living there for over a month. I never saw him with warm clothing or food. I knew what I wanted to do.When I told my parents what I wanted to do they werealarmed. They said I could be putting myself at risk, taking a box to a homeless person at night! But I knew, in my deep heart, that I would be safe.I got a box. My parents watched as I added warm gloves, a heavy blanket ... into the box until it was full! Then, I put a Christmas card on top. It said, “Even though we hardly know each other, I want to wish you a Merry Christmas!” I put ten one-dollar bills inside it as well.My father insisted he went there with me as it was 10 pm on Christmas Eve. I said he could drive me but he had to stay in the car. He agreed.I took the box and walked towards his “house”. I called, “Sir, I have a Christmas box for you!”“Go away!” he shouted.“Sir,” I repeated.“Go away!” he shouted.“Why?” I asked him.He walked over and I expected to see an angry face. Instead I saw two of the most beautiful, gentle, blue eyes I have ever seen.“Merry Christmas!” I said.“Why are you doing this?” he asked.“Because you matter to me,” I said. With that I gave him the box.Tears came to his eyes and he thanked me. I got back to the car and watched him carry the box like it was filled with gold. I didn’t want to embarrass (使困窘) him by watching him any more so Dad and I left.12. The underlined word “alarmed” can best be replaced by _____.A. pleasedB. worriedC. disappointedD. surprised13. Why did the author ask his father to stay in the car?A. Because he wanted to prove he was brave.B. Because he believed the homeless man was bad.C. Because he wanted to protect his father from being hurt.D. Because he didn’t want the homeless man to feel bad.14. When the homeless man saw the author first, he was _____.A. quite angryB. very excitedC. quite puzzledD. very curious15. The author’s purpose in writing the text is to tell readers that _____.A. it is easier said than doneB. poverty is the mother of healthC. where there is a will, there is a wayD. a willing helper doesnot wait until he is asked第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

浙江省宁波市鄞州区2021-2022学年七年级下学期期中联考英语试题

浙江省宁波市鄞州区2021-2022学年七年级下学期期中联考英语试题

浙江省宁波市鄞州区2021-2022学年七年级下学期期中联考英语试题学校:___________姓名：___________班级：___________考号：___________一、完形填空It’s five o’clock in the afternoon. School ____1____ and the students from Class 3 are going to Grandma Liang’s house. Grandma Liang is ____2____ years old and she has no____3____ or daughters, so the children often go to help ____4____ do some things. Now the children are at Grandma Liang’s home. Grandma Liang is very ____5____ to see them. She thinks these children are very ____6____. Look! Lily is talking with Grandma Liang in the living room. She knows that Grandma Liang always feels lonely（孤单）____7____ she doesn’t have ____8____ to talk to. Betty is cleaning the ____9____. Grandma Liang is too____10____ to do it by herself. Jane is ____11____ clothes outside the room. ____12____ is Ann? Oh, she is in the kitchen. She’s making ____13____ for Grandma Liang. She knows Grandma Liang’s favorite ____14____ is tomatoes. What is Jim doing? He is in the kitchen, too. He is ____15____ Ann. What good children they are!1．A．comes B．goes C．finishes D．gets2．A．7B．70C．17D．30 3．A．sisters B．sons C．aunts D．brothers 4．A．him B．you C．me D．her 5．A．afraid B．sorry C．happy D．relaxed 6．A．smart B．nice C．strict D．scary 7．A．after B．because C．before D．so 8．A．anyone B．someone C．no one D．everyone 9．A．cars B．windows C．head D．teeth 10．A．old B．young C．strong D．good 11．A．doing B．taking C．making D．washing 12．A．What B．How C．When D．Where 13．A．breakfast B．clothes C．lunch D．dinner 14．A．drink B．meat C．food D．fruit 15．A．watching B．helping C．calling D．finding二、阅读单选16．Who is Bing Dwen Dwen?A．A tiger.B．A panda.C．A dragon.D．An elephant.17．How long did it take to create Bing Dwen Dwen?A．One year.B．A week.C．Ten months.D．2022 days. 18．What’s the meaning of “mascot”?A．火炬B．会旗C．会徽D．吉祥物The Dragon Boat Festival（端午节）is a very important Chinese festival. It is on June 5th this year.People always think of Qu Y uan, a great poet（诗人）of Chu, at the festival. Qu Yuan jumps into the Miluo River to show his love to his country. People throw（扔）zongzi into the river to feed the fish, so the fish will not eat Qu’s body. After that, every year on this day, people eat zongzi to remember him. But people in different places eat different kinds of zongzi. People in southern China like eating meat zongzi. In the north, people often eat sweet zongzi.The dragon boat race is also a/an ________ activity. It is one of the national（国家的）sports. The races are very interesting and exciting. Usually, a dragon boat is about 20 to 30 meters long. This year, people in Guizhou make a very long one. It is about 77.8 meters. We can see many special and funny dragon boats from different places on TV and watch these dragon boat races on TV, too.19．People throw ________ into the river to let fish not eat Qu’s body.A．meat B．zongzi C．sweets D．dumplings 20．Which of the following words can be put in the in Paragraph 3?A．important B．friendly C．dangerous D．difficult 21．Why do People eat zongzi on the Dragon Boat Festival?A．Zongzi is very delicious and they can eat sweet zongzi or meat zongzi.B．They want to watch these dragon boat races on TV.C．Quyuan is a great poet and he loves his country.D．They want to remember Quyuan.22．Which is the best title（标题）for the article?A．The great poet of China.B．The Dragon Boat Races.C．The Dragon Boat Festival.D．The Dragon Boat in Guizhou.Oh, the rain! How Sara hates the rain! She cannot go outside to meet her friends for a game. Her mother says to her, “You may catch a cold if you play in the rain.” But Sara shouts, “It’s raining, but it’s very hot outside!” Her mother still doesn’t let her out in the rain.Sara goes up to her room and lies down in front of her window. In fact, she has many things to do in her room. There is a TV, some books and toys. But she doesn’t like any of them. She opens the window so the rain can hear her. She wishes the rain away but that doesn’t work. “Well, if you’re going to be here and ruin my day, please find something interesting for me to do.” She shouts and again gets no answer. So she sits back down on the window. It is still raining. “Fine,” she thinks. “I can go swimming, ride my bike and play with my friends when the rain stops.” She thinks about her ideas again and again. How she wishes the sun to come out! Soon she falls asleep on the window. She hopes to do all she wants in her dream.23．What’s the weather like that day?A．Rainy and hot.B．Rainy and cold.C．Cold and sunny.D．Hot and sunny. 24．Why doesn’t Sara’s mother let Sara out ?A．Because Sara may catch a cold.B．Because Mom wants Sara to do some reading.C．Because Mom thinks it’s not interesting to play in the rain.D．Because it’s time for Sara to sleep.25．We can infer (推测) that Sara may ________ when the rain stops.A．watch TV B．read books C．play with toys D．ride her bike 26．What can we learn from the passage?A．The rain stops and the sun comes out.B．Sara finally falls asleep by the window. C．Sara’s mother lets her out at last.D．Sara finds something interesting to do.Can you play a game called “Musical Chairs”? It is easy to play and most people enjoy it. All you need are some chairs, some people and some ways of making music. You may use a piano or any other musical instrument, if someone can play it. You may use a tape recorder. You can even use a radio.The game is easy. Put the chairs in a circle. When the music starts, the players walk round the chairs. Everyone goes in the same direction. Of course, they should walk in time to the music. If the music is fast they should walk quickly. If the music is slow, they should walk slowly.The person playing music cannot see the people in the game. When the music stops, the players try to sit on the chairs. If a person cannot find a chair to sit on, he drops out（退场）. Then, before the music starts again, one chair must be taken away. When the music stops again, one more player will be out.At last, there will be two players and only one chair.The one who sits on the chair when the music stops is the winner（获胜者）.27．If ten people are playing musical chairs, you must begin with _________.A．nine chairs B．ten chairs C．eleven chairs D．one chair 28．Which of the following is NOT suitable （合适的）for playing “Musical Chairs”? A．A piano.B．A radio.C．A violin.D．A telephone. 29．When the music starts, the players must ________.A．run about the room B．get down C．walk around the chairs D．sit on the chairs30．Which of the following statements is NOT true?A．The game “Musical Chairs” is not difficult to learn.B．At last, there will be two players and two chairs.C．The winner can sit on the last chair.D．If the person plays music, he cannot see the people in the game.三、阅读匹配以下是对于中国五个城市的气候描述，请根据描述选出正确的城市。

浙江省宁波市鄞州区七校七年级数学下学期期中试题浙教版(2021年整理)

浙江省宁波市鄞州区七校七年级数学下学期期中试题浙教版(2021年整理)

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（满分100分 测试时间90分钟)一：选择题（每小题3分,共30分） 1．下列运算正确的是（ ） A ． a 2•a 3=a 6B ． (a 3）2=a 5C ． （3ab 2）3=9a 3b 6D ． a 6÷a 2=a 42．若是关于x ．y 的方程2x ﹣y+2a=0的一个解,则常数a 为( ）A ．1B ．2C ．3D ．43．世界上最小、最轻的昆虫是膜翅缨小蜂科的一种卵蜂，其质量只有0.000005克,50只这种昆虫的总质量是（ ）A ．6105-⨯B ．51025-⨯C ．4105.2-⨯D ．5105.2-⨯ 4．如图，直线a ∥b ，∠1=120°，则∠2的度数是( ） A ．120° B ．80°C ．60°D ．50°（第4题图） (第5题图）5．如图所示，在下列四组条件中，能判定AB ∥CD 的是（ ） A ．∠1=∠2 B ．∠ABD=∠BDC C ．∠3=∠4 D ．∠BAD+∠ABC=180° 6．下列代数式变形中,是因式分解的是（ ）A ．ab ab b ab -=-221)2(21 B ．)2(3363y x y x -=+-C ．1)3(132+-=+-x x x xD ．22)1(12--=-+-x x x7．计算))()((22b a b a b a -+-的结果是（ ) A ．42242b b a a +- B ．42242b b a a ++ C ．44b a + D ．44b a － 8．80803-能被（ )整除A ．76B ．78C ．79D ．82 9．已知x 2+y 2+4x ﹣6y+13=0，则代数式x+y 的值为（ ） A ． ﹣1B ． 1C ． 25D ． 3610．已知关于x ，y 的方程组⎩⎨⎧-=-=-52253a y x ay x ，则下列结论中正确的是（ ）①当a =5时，方程组的解是⎩⎨⎧==2010y x ；②当x ，y 的值互为相反数时，a =20;③不存在一个实数a 使得x =y ；④若73222=-y a ，则a =2．A ．①②④B ． ②③④C ．②③D ．③④ 二:填空题:(每小题3分，共24分）11。

2020-2021学年宁波第七中学高三英语下学期期中考试试卷及答案

2020-2021学年宁波第七中学高三英语下学期期中考试试卷及答案

2020-2021学年宁波第七中学高三英语下学期期中考试试卷及答案第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项AThe OrchardI had a very nice meal at the Orchard restaurant．The food was lovely and the service was quite good．We chose to eat in the garden which was full of beautiful flowers and very relaxing．The only disappointment was the dessert — the apple piewas far too sweet and it was cold too．Apart from that it was an enjoyable evening．As for the price — what a bargain，excellent value for money！Park InnThe best thing about Park Inn was the service — it was excellent．There was a warm welcome when we arrived and the waiters were very helpful all evening．However，the food wasn’t as good．The menu looked interesting but the meals were rather tasteless．It’s not a cheap restaurant and I wasn’t happy to pay so much for boring food．Richard’s PlaceWhen we enteredthe restaurant，we were surprised by the lovely interior (内部的) design of it．So stylish，so modern！This is one of the most popular restaurants in town and it’s very easy to see why．The food was great and excellent value for money but it was ruined by very，very poor service！TheRiversideIt was lovely sitting outside and looking over the river．There were lots of little lanterns (灯笼) and color1 ed lights everywhere and it all looked very pretty．The food was good，nothing very special but quite tasty．The service was OK; we didn’t have to wait too long for our food but the waiter never looked very happy！It’s quite an expensive place but with the view I think it’s quite good value for money．1. In which restaurant can customers eat in the garden？A. Park Inn．B. TheOrchard．C. The Riverside．D. Richard’s Place．2. What makes the customers of Park Inn most satisfied？A. The food．B. The price．C. The service．D. The environment．3. In Richard’s Place，customers can ________．A. receive good serviceB. enjoy its moderndesignC. listen to wonderful musicD. enjoy the beauty of a riverBHaley Curfman, 25, of Blackwell, Oklahoma, is a teacher at Blackwell Public School and last yearshe bought a plain(朴素的) white dress, which she set up a station in her classroom for her students to decorate, encouraging them to go and draw on the dress whenever they had free time. Haley set up a station at a table with the dress and some color1 ed markers so that her students could draw on it, having first seen the idea on Pinterest.After the kids had finished the design, she then surprised them all by wearing the dress to class, sharing pictures of herself in it on Facebook in a post that has since been shared over 200, 000 times.For teachers looking to do something similar for their own students, Haley said that she bought the dress off Amazon for less than $ 20 about six months ago and pre-washed the dress before she started the project. She used markers from Walmart. But she said these things can be bought in other places. She said, “To do the project, I set up a station at a table with the dress and markers. It takes anywhere from two weeks to a month to complete as we just work on it here and there when time allows. You'd better give the students enough time so they don't have to hurry.”“Teachers have been sharing their dresses, T-shirts, etc. with me that they've been creating since the 1950s with the same idea. It is amazing, and I love the fact that you are sharing them with me! Thank you all so much for your kindness and support,” she wrote on Facebook.Asked why she came up with the idea, Haley told Scary Mommy. “We don't have art in our school, so, I always try to do little creative projects when possible.”4. What did Haley use the plain white dress to do?A. To teach her students painting.B. To prepare for her presentation.C. To ask her students to draw on it.D. To help her students with their homework.5. What do we know about the finished dress?A. It took Haley by surprise.B. It is kept by Haley at home.C. It is the product of a new idea.D. It has enjoyed popularity online.6. What should a teacher do if he or she wants to follow Haley's example?A. Buy the same dress online.B. Give the kids enough time.C. Buy the same markers in Walmart.D. Leave the finished work untouched.7. Why did Haley carry out the project?A. To teach art to her students.B. To show her idea on Pinterest.C. To share it with other teachers.D. To exciteher students' creativity.CInAsia, there are special competitions where kites have complex designs and are fitted with instruments that make musical sounds as the wind blows through them. Although all kites have a similar structure (结构), they are widely different in size and shape. Kite-fighting competitions are also held, in which competitors use their kites to attack and bring down their opponents’ (对手) kites or cut their strings (线).For more than 15 years, the Big Wind Kite Factory has been giving kite-making and kite-flying classes for the children on an island inHawaii. In its kite-making lessons, students can make kites in as little as 20 minutes! Children as young as four years old can learn how to fly a kite. Jonathan Socher and his wife Daphne started the kite factory in 1980. Their kites are made of nylon (尼龙). Their designs are Hawaiian themes created by Daphne. The designs are cut out of the nylon with a hot knife that seals the edges and then fastened directly onto the kite. The kite that is used to give lessons is a regular diamond kite with a rainbow pattern. The difference between this kite and the ones they make during the lessons is that it is a two-string controllable kite. Big Wind employees fly the kite and for a few minutes show students how pulling on one line and then on the other controls the direction the kite goes in. Then the controls are given to the students.Jonathan insists that it is not necessary to make a huge impressive kite to have fun making and flying kites. Even the simplest structure can work, and can give hours of fun. Go on, give it a try!8. Which of the following is true according to the text?A. A hot knife is used to iron the nylon.B. Children never fly kites on their own in flying lessons.C. Kite strings must not be cut in kite-fighting competitions.D. Daphne designs kites for the Big Wind Kite Factory.9. What is different about the kite used for flying lessons?A. It has two strings.B. It is simple in design.C. It has a rainbow pattern.D. It is shaped like a diamond.10. According to Jonathan,what do you need to have fun with kites?A. A large kite.B. Any type of kite.C. A complex structure.D. A kite that impresses others.11. What is mainly described in the text?A. A kite factory.B. Kite-flying lessons.C. Special competitions.D. The kite-making process.DJerry Lawson had a love of science and invention from a very young age. And, with the support of his family and teachers, he took that love and helped change the world for billions of people, when he invented the modem video game cartridge.Both of Jerry's parents supported his love of science and invention. His father, a longshoreman, was a science fan and encouraged Jerry to always experiment with things. Jerry's first-grade teacher helped encourage him on his path to be someone influential similar to George Washington Carver, a great AfricanAmerican inventor. His first love in school was chemistry but he ended up liking electronics（电子学）even more.He earned an amateur ham radio license at age 13 and built his own radio station in his room, with an antenna hanging out of his window! Jerry earned money from fixing television sets, visiting people's homes for inhouse repair, and also working at local electronics stores. Jerry also made walkie-talkies and sold them to other kids. He spent many Saturdays at an electronics store that had all of the parts he needed for his inventions. He would use his small allowance and money he earned to buy parts to help fuel his inventions.When he was a young adult, Jerry joined Fairchild Semiconductor as an engineer. During this time, he created his own video arcade game（街机游戏），Demolition Derby, in his garage.A few years later, Jerry was asked to work on a secret project. Not even his boss was allowed to know what he was doing! What it turned out to be was that he was designing the Fairchild Channel F video gameconsole（游戏控制器）and leading the team that invented the video game cartridge. This was the first of its kind and enabled kids around the world to affordably play video games at home.Just like with automobiles，many advances have occurred since the inventionof video games. Video games are now one of the biggest forms of entertainment in the world. But all of this would not have been possible without the vision, passion, and skill of Jerry Lawson and his learn.12. How did Jerry earn money when he was a teenager?A. By running his radio station.B. By selling television sets.C. By repairing things for others.D. By making electronic parts.13. Before Jerry's secret project, playing video games at home was_____.A. expensiveB. harmfulC. commonD. tiring14. What does the author mainly tell us in the last paragraph?A. Jerry Lawson and his team can be more skillful.B. Jerry Lawson is important to the game industry.C.Many advances have taken place in the automobile industry.D. Video games are now the most popular form of entertainment.15. What can be the best title for the text?A. Video Gaming-An Important IndustryB. Game Console-Key to Home Video GamesC. Jerry Lawson-Father of Modern GamingD. Support and Encouragement-Necessary for Success第二节（共5小题；每小题2分，满分10分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

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2020学年第二学期七年级科学期中测试卷一、选择题（本题共20小题，每小题2分，共40分。

请选出每小题中一个符合题意的选项，不选、错选均不给分）1．2020年秋冬以来，雨水较少，宁波市皎口水库见底，古村遗址重现人间，节约用水，你我同行。

下列关于水资源说法错误的是（ ）A ．淡水资源是取之不尽，用之不竭的B ．地球上大部分是含盐量很高的海水C ．为减少水体污染，农药、化肥要合理使用D ．为节约用水，农业、园林浇灌改为喷灌、滴灌2．空气成分中，体积分数最大的是（ ）A ．氮气B ．氧气C ．二氧化碳D ．稀有气体3．厨房锅里油着火，下列应急措施中正确的是（ ）A ．立即用嘴用力吹B ．立即往锅里加入冷水C ．立即把锅里的油倒掉D ．立即用锅盖盖上4．证明汽水中含有二氧化碳气体，最合理的做法是（ ） A ．B ．C ．D ．5．自然界中的云、雨、雪、雾、露、霜等现象，都是水的物态发生变化形成的，图中描述的物理现象理解正确的是（ ）A ．雾是汽化现象B ．露是液化现象C ．霜是升华现象D ．雪是凝固现象6．超临界二氧化碳流体是一种具有和水相似、能阻燃、溶解能力强的溶剂，被誉为“绿色环保溶剂”。

下列说法正确的是（）A．常温下二氧化碳能供人体呼吸B．少排放二氧化碳可减少对臭氧层的破坏C．超临界二氧化碳流体是一种特殊的物质，容易燃烧D．超临界二氧化碳流体可代替许多有害、有毒、易燃的溶剂7．通过小孔所成的像一定是（）A．倒立的B．放大的C．等大的D．缩小的8．下列变化中，属于缓慢氧化的是（）A．二氧化碳使澄清石灰水变浑浊B．食物的腐烂C．实验室制取氧气D．红磷燃烧9．保持温度不变，小心蒸发氯化钠不饱和溶液（蒸发皿中始终有溶液），则溶液中溶质的质量分数（m%）与时间（t）的关系合理的是（）A B C D10．蜡烛(足量)在密闭的集气瓶内燃烧至熄灭，用仪器测出瓶内氧气含量的变化如图所示。

下列判断正确的是( )A．蜡烛燃烧前瓶内只有氧气B．蜡烛熄灭后瓶内没有氧气C．氧气浓度小于一定值时，蜡烛无法燃烧D．蜡烛熄灭后瓶内只剩二氧化碳气体11．将装有碎冰的试管，插入装有冰粒的烧杯中间，然后用酒精灯给烧杯加热，当烧杯中的冰熔化一半时，试管中的冰()A．没有熔化B．熔化一半C．熔化小于一半D．熔化超过一半12．将适量的下列物质溶解于水的过程中，会使溶液的温度显著降低的是（）A．食盐B．氢氧化钠C．硝酸铵D．蔗糖13．下列关于阳光的说法错误的是( )A．阳光由红、橙、黄、绿、蓝、靛、紫七种色光组成B．紫外线具有杀菌作用，因为紫外线具有较大的能量C．红外线的热效应显著，可以加热物体D．紫外线可用于检测纸张上是否含荧光剂14．同学在“研究影响液体蒸发快慢的因素”时，选用两块完全相同的玻璃片，分别在玻璃片上滴一滴水和酒精，放在同一张实验桌上，如图所示。

观察图中情景可知，该同学主要研究蒸发快慢是否与()A．液体的温度有关B．液体的种类有关C．液体的表面积有关D．上方空气的流速有关15．下列物质在氧气中燃烧，对主要现象的描述错误的是()A．氢气燃烧，产生淡蓝色火焰B．磷燃烧，产生大量的白烟C．铁丝燃烧，发生蓝紫色火焰D．木炭燃烧，发出白光16．每年3月，院士公园郁金香绽放，小明将红色滤色镜（即红色玻璃）挡在照相机镜头前，给一株绿叶黄花的郁金香拍照，照片上该花卉的颜色是（）A．绿叶黄花B．黑叶红花C．黑叶黑花D．红叶红花17．如图是电解水的示意图，关于电解水的下列说法中，不正确的是() A．此实验得出结论，水是由氢和氧组成的B．理论上若得到6mL的氢气，可同时得到12mL氧气C．电解水时需通直流电D．与电源正极连接的试管内，产生的气体能使带火星的木条复燃18．实验桌上放置了一个带胶塞的，体积为1L的烧瓶，①第一位同学说：烧瓶内没有东西；②第二位同学说：瓶内有东西，只能凭想象，不能用实验证明；③第三位同学说：把它放在天平上称量出来的质量，正好是1L空气的质量；④第四位同学说：将瓶倒置盛水的水槽中，水不能进去；略斜口露出一点，则水进入瓶内，并形成一串气泡，说明瓶内有东西。

你认为正确的叙述是( )A．②和③B．只有①C．③和④D．只有④19．今有60g溶质的质量分数为10%的氢氧化钠溶液，欲将其溶质的质量分数增大一倍，应采用的方法是( )A．把溶剂蒸发掉一半B．加入6g氢氧化钠固体C．把溶剂蒸发掉30g D．加入20%的氢氧化钠溶液30g20．如图所示为蒸发氯化钠溶液的实验过程，其中①→②→③为恒温蒸发过程，③→④为升温蒸发过程，②溶液恰好为饱和状态，分析实验过程，可以作出的正确判断是（）A．在①→②过程中，氯化钠的质量分数保持不变B．在②→③过程中，氯化钠的溶解度不断增大C．在③→④过程中，氯化钠的质量分数不断减小D．在②→④过程中，氯化钠的质量分数先不变后增大二、填空题（本题共4小题，每空2分，共24分）21．地球上存在着不同形式的水体，如海洋水、冰川水、地下淡水、湖泊咸水等，其中占地球总量最多的是__水，右图是大自然中水循环示意图，写出图中③所代表的物态变化名称__，这一过程要__（填“吸热”或“放热”）22．氧气是一种化学性质比较活泼的气体，它可以和许多物质发生化学反应。

如图所示是硫粉、红磷、光亮的细铁丝在氧气中燃烧的实验装置：（1）小科是个善于思考、善于总结的学生。

做完实验后，他发现在反应条件方面，三个实验都要。

（2）小科同时也总结出在生成物的种类、生成物的状态和观察到的实验现象三个方面存在不同。

请你替小科同学填写空格：乙中生成物的名称是。

甲中观察到的反应现象是。

（3）小科还总结出：三个实验的集气瓶底部都放有少量水，其中丙集气瓶底部放少量水的目的是。

23．“对比实验”是科学学习中行之有效的思维方法。

某科学学习小组在实验室做了如图所示的对比实验，请回答下列问题：（1）通过实验A，可说明燃烧的条件之一是______（2）实验B能证明氢氧化钠溶液与CO2发生反应的证据是________ 。

24．小科利用如图所示装置探究冰的熔化特点，他每隔相同时间记录一次温度计的示数，并观察物质的状态。

（1）图甲是他根据记录的数据绘制的“温度一时间”图像。

由图像可知：冰熔化的特点是吸热，温度。

（填“升高”、“降低”或“不变”）（2）图甲中第3min时，物质处于态。

（填“固”、“液”或“固液共存”）（3）为使实验现象更加准确、明显，应选用颗粒（选填“较大”或“较小”）的冰块做实验三、实验探究题（本题共3小题，每空2分，共22分）25．小科为了研究物体吸热性能与物体表面颜色的关系，他在两个相同的容器里倒入质量不同的水（m甲<m乙），并用白纸（甲）和黑纸（乙）包起来并放在太阳光下，如图每隔3min测一次容器中液体的温度。

得到两容器中水温变化情况如下表所示。

由此小科同学得出的结论是：表面颜色浅的物体吸热本领较强。

你认为小科的实验方法_____________ (填“正确”或“不正确”)，若你认为不正确，帮他改正________________________________________ 。

26．为了验证二氧化碳的性质，某同学将实验中制取的二氧化碳气体导入A，B装置，回答下列问题：（1）装置A中紫色石蕊试液变红，是因为生成某酸性物质，请写出发生反应的文字表达式为；（2）B装置中的现象是，说明二氧化碳，且密度比空气。

27．某同学欲配制80g 5%的NaCl（氯化钠）溶液。

该实验的部分操作如下图所示。

（1）需要称取氯化钠的质量是____g，若称量时A出现了右盘略低的现象，接下来的具体操作是__________。

（2）量取水时，应选用规格为100mL的量筒，而不选用200mL的量筒，其目的是；（3）C中用玻璃棒搅拌的作用是________________________。

（4）以下操作会导致配制的氯化钠溶液质量分数偏小的有_______________。

A．在托盘天平的左盘称取氯化钠时，游码不在零位置就调节天平平衡，后将游码移动得到读数；B．氯化钠固体不纯；C．按照图B的方法读数；D．将量筒中的水倒入烧杯时，有水洒出；四、解答题（本题共2小题，第28题5分，第29题9分，共14分）28．小科家下面是一个水果市场，夏天的时候，她观察到卖西瓜的小贩无论天晴、下雨，总会撑起一把巨大的红色遮阳伞，而卖香蕉的小贩又会撑起一把黄色的遮阳伞，她百思不得其解，请你帮她解释原因。

29．20℃时，向甲烧杯中加入100g水和25g固体A，向乙烧杯中加入100g水和25g固体B （A、B两种物质均不与水反应）。

充分搅拌后，甲烧杯中固体剩余，乙烧杯中固体全部溶解．请回答下列问题：（1）20℃时，甲烧杯中溶液是___________（填“饱和”或“不饱和”溶液）；一定能使甲烧杯中的固体A继续溶解的方法是_________________。

（2）求乙烧杯中B溶液的溶质质量分数（请列式计算）2020学年第二学期七年级科学期中测试卷参考答案一、选择题（本题共20小题，每小题2分，共40分。

请选出每小题中一个符合题意的选项，21、海洋、蒸发、吸热22、(1)点燃(2) 五氧化二磷、发出蓝色火焰，放出大量热，生成一种有刺激性气味的气体(3)防止生成的熔融物溅落下来，使集气瓶破裂23、(1)温度达到可燃物的着火点(2)②塑料瓶变扁的程度要比①大24、(1)不变 (2) 固(3)较小三、实验探究题（本题共3小题，每空2分，共22分）25、(1)不正确(2) 两个相同的容器倒入等质量的水26、(1)二氧化碳+水→碳酸(2)蜡烛由下往上熄灭、不燃烧也不支持燃烧、大27、(1)4、往左盘继续加氯化钠直至天平平衡(2)减小误差(3)搅拌，加速溶解 (4) ABC四、解答题（本题共2小题，第28题5分，第29题9分，共14分）28、撑一顶红色半透明的遮阳伞，阳光照射在伞上时，阳光中的红光能透过伞而照在西瓜上，瓜瓤看起来是红色的（2分）；黄色半透明的遮阳伞可以通过黄光，把其它颜色的光吸收掉，与香蕉的颜色相同．香蕉看起来更黄（2分），使得西瓜、香蕉更好卖（1分）。

29、(1)饱和、加水（加溶剂）(2)20%。

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