课时作业2
2020-2021学年语文人教版必修2课时作业:第2课 故都的秋
课时作业2故都的秋第一课时基础巩固一、积累运用1.下列加点字的读音完全正确的一项是(C)A.一椽.(yuán)廿.四(niàn)扫.帚(sào)B.潭柘.寺(zhé)房檩.(lǐn)普陀.山(tuó)C.平仄.(zè)譬.如(pì)厦.门(Xià)D.椭.圆(tuǒ)落蕊.(ruǐ)橄.榄(gān)解析:A项,“椽”应读“chuán”;B项,“柘”应读“zhè”;D项,“橄”应读“gǎn”。
2.下列句子中加点的成语使用错误的一项是(C)A.我的不远千里....,要从杭州赶上青岛,更要从青岛赶上北平来的理由,也不过想饱尝一尝这“秋”,这故都的秋味。
B.在华语乐坛上占有特殊一席的女歌手齐豫即将在北京举办演唱会,然而在发布会上,齐豫却不能自已....地泣不成声,因为她宣称这将是自己最后一次举办演唱会。
C.显然,打造“信用政府”和发展“民营经济”这两个热点,在民众的关怀下不期而遇....。
D.一个明智的人应当具有一叶知秋....、举一反三的能力。
解析:A项,不远千里:不以千里为远。
形容不怕路途遥远。
使用正确。
B项,不能自已:无法控制自己,使激动的情绪平静下来。
使用正确。
C项,不期而遇:没有约定而意外地相遇,适用于人。
此处用错对象,此处是指“信用政府”和“民营经济”惠及民众。
D项,一叶知秋:从一片树叶的凋落,知道秋天的到来。
比喻通过个别的细微的迹象,可以看到整个形势的发展趋向与结果。
使用正确。
3.下列句子中加点虚词使用不正确的一项是(B)A.我虽.则外国诗文念得不多,也不想开出账来,做一篇秋的诗歌散文钞。
B.若.你去一翻英德法意等诗人的集子,或各国的诗文的Anthology来,总能够看到许多关于秋的歌颂与悲啼。
C.南国之秋,当然是也有它的特异的地方的,譬如..廿四桥的明月,钱塘江的秋潮,普陀山的凉雾,荔枝湾的残荷等等,可是色彩不浓,回味不永。
人教版七年级数学上册教师用书配套课件 课时作业 (2)
自主解答:B
名师点津:有关线段的计算注意问题 1.线段的长度和有理数一样,可以进行加减等运算. 2.如果题目中没有图形,一定要先画出图形,数形结合思想 是数学学习的一种重要方法,应特别注意对线段的中点的灵活运 用.
知识点 3 线段性质的应用 【例 3】平面上有 A,B,C,D 四个村庄,为解决当地缺水 问题,政府准备投资修建一个蓄水池,不考虑其他因素,请你画 图确定蓄水池 H 的位置,使它与四个村庄的距离之和最小(A,B, C,D 四个村庄的地理位置如图所示),你能说明理由吗?
自主解答:解:(1)3; (2)当 PA=PB 时,点 P 的位置有两种情况: ①P 为 AB 的中点,此时 PA+PB=AB;②P 不在 AB 上,此 时 PA+PB>AB. 规律总结:比较线段长短的方法 1.度量法:用刻度尺量出两条线段的长度,再比较长短. 2.叠合法:利用直尺和圆规把线段放在同一条直线上,使其 中一个端点重合,另一个端点位于重合端点同侧,根据另一端点 与重合端点的远近来比较长短.
知识点 1 线段的比较与画法 【例 1】已知线段 AB=8,平面上有一点 P. (1)若 AP=5,PB 等于多少时,点 P 在 AB 上? (2)当 PA=PB 时,确定点 P 的位置;并比较 PA+PB 与 AB 的大小.
思路点拨:(1)只有 AP+PB=8 时,点 P 在 AB 上; (2)要分类讨论,点 P 的位置有两种情况.
A.3 cm C.11 cm
B.6 cm D.14 cm
解析:∵D 是 AC 的中点,∴AC=2DC,∵CB=4 cm,DB =7 cm,∴CD=BD-CB=3 cm,∴AC=6 cm,故选 B.
2.已知线段 AB=8,延长 AB 到点 C,使 BC=12AB,若 D 为 AC 的中点,则 BD 等于( B )
2023版新教材高中英语Unit2TravellingAround课时作业二Di新人教版必修第一册
课时作业(二) Discovering Useful Structures &Listening and T alking必备知识基础练进阶训练第一层Ⅰ.单词拼写1.The ________ (景色) from the top of the tower was wonderful.2.The little boy opened two ________ (包裹) of cookies.3.The newly built school library will be a useful________(来源)of information for us.4.Please supply the following ________ (细节): name, age and sex while filling in the form.5.China's efforts in the ________ (经济的) growth and poverty alleviation (扶贫) fight set a good example for other countries in the world.6.The peak (高峰) of train ________ (交通运输系统) is expected to appear on Wednesday, Oct.1—the first day of the National Day holiday.Ⅱ.单句语法填空1.It is reported that a 3% ________ (economy) growth is the government's aim.2.Provide the doctor with your ________ (detail) medical history so that you can get a better treatment.3.It was ________ (believable) that the fans waited outside the gym for three hours to have a look at Y ao Ming.4.Jane saw her sister off at the railway station, waving until the train was out ________ sight.5.Lucy made a speech in the English class, and the teacher asked us tomake some comments ________ her performance.6.They had an accident on the road, so they didn't check ________ at their hotel until midnight.7.In Britain, women today make ________ 44% of the workers and nearly half the mothers with children are in paid work.8.In middle schools of that country, boys are requested not ________ (wear) long hair.9.My parents ________ (take) me to Beijing to visit T singhua University next weekend.10.Varieties of waste flew into the water in the past, ________ (kill) river and sea life.Ⅲ.单元语法练习1.When our guest ________ (arrive), I will pick him up at the airport.2.Sophia ________ (go) to the airport because she has to pick up her grandma tonight.3.Ladies and gentlemen, please turn off your cellphones or laptops. The plane ________ (take) off.4.If you ________ (come) to my hometown next month, I'll treat you to a big dinner.5.We ________ (fly) to Shanghai tomorrow so we'd better get our package packed now.6.Please call the station to make sure when the earliest train ________ (leave).7.Close the door of fear behind you, and you ________ (see) the door of faith open before you.8.Mary ________ (leave) for Shenyang by plane at 3:00 this afternoon.Ⅳ.完成句子1.他两小时后将赴伦敦和经理会面。
课时作业2:Unit 4 第二课时
Why don’t you talk to your parents?Section A (3a-4c)一.用词的适当形式填空:1. Last year he usually felt bored with his study and his grades ____________(drop).2. Do you mind __________(open) the window?3. I want to do it in a p_________way. But I don’t know how to do it.4. Alice ________ (厌恶)to do the dishes, but she likes sweeping the floor.5. Playing computer games too much is a ________(浪费) of your time.6. My bike is broken. Could you ________ (借给)me yours, please?7. His parents are very busy. They have little time to c ________with their children.8. He is ready to help others, and he always o money to the people in the poor villages.9. If you borrow books from the library, you should r ___them on time.10. I feel really n _____(紧张的)before the final examination.11. P ______(也许)he will come for afternoon tea,but I’m not sure.12.When I came in, I found him _________(write) something on his seat..13.A Malaysia airplane was missing on March 8th, can you i what happened to thisplane? Was it exploded (爆炸)or being hijacked (劫持了)?14. We should tell them ____________(not wear) the unusual clothes.15. We must study hard and be a ______________(success)person.16. There parents aren’t here,so they look after ________________(they).17. This is a _______________(type) farmer family.18. China is improving(改善)___________(关系)with other countries.19. I don’t know when he will come tomorrow. I will call you as soon as he _______(arrive)20. W_________I said, he didn’t agree with me.二.单项选择:1. I had a hard time with math and I wasn’t ______ to get the bad report from my math teacher.A. sureB. surprisedC. excitedD. interested2. I’m going to take a vacation. Could you please _____me _____some information aboutinteresting places to travel?A. offer, toB. offer, forC. provide, withD. provide, for3. Few people think about what they can do _______others.A. helpB. to helpC. helpingD. helped4---Do you mind _________your room?---No, I’l l do that after finishing _________this article.A. clean, writeB. clean, writingC. cleaning, writeD. cleaning, writing5. Mr. Black asks the kids ________ in the river, because it’s too dangerous.A. swimB. to swimC. not to swimD. swims6. Mr.Li asks us to remember that ____careful we are,_____mistakes we will make.A. the more,the lessB.the more, the moreC. the more, the fewerD. the less, the fewer7. Mary’s grandpa is always ______ in the mountain village.He tells her he feels very______. So she’s going to visit him next week.A. alone; aloneB. lonely; lonelyC. lonely; aloneD. alone; lonely8. Thank you for your help, Linda. You made ________ possible for us to finish the work in time.A. thisB. itC. themD. that9. My sister ______ go to bed _______ my mother came back last night.A. not untilB. doesn't; untilC. didn't; untilD. aren't; until10. Can you _______ me your bike?---With pl easure. But you mustn’t ____ it to others.A. lend, borrowB. borrow, lendC. lend, lendD. borrow, borrow11. ---I am not going swimming tomorrow afternoon.----_____. I have to clean up my bedroom.A. So am IB. Neither am IC. neither I amD. so I am12. Could you please_____ the piano so loudly? Your brother is having a rest now.A. not to playB. not playC. don’t playD. to not play13. This math question is too difficult. Can you help me ?A.work on itB.work out itC.work it outD.work for it14.—What’s wrong?—I can’t do my homework now. I my homework in the classroom this morning.A.leaveB.forgetC.forgotD.left15. He is very angry with his mother, because his mother always him with the best student.paresplainsC.tellsD.makes16. He should the teacher.A.explainB.explain toC.explainedD.explained to17. —— Hurry up. The bus is coming!——Oh, no, we mustn’t cross the street ______ the traffic lights are green.A. afterB. sinceC. whenD. before18. ---Could I watch TV? ---No, you ___. You ____finish your homework first.A. can’t, mustB. can’t, canC. couldn’t, mustD. couldn’t, can19. ---Could I _____your bicycle? ---Sure, and you can ______for a week.A. borrow, borrowB. borrow, keepC. lend, lendD. lend, borrow20. Mary will make a plan as soon as she ____________her homework.A. finishesB. finishC. will finishD. finished参考答案一. 1dropped, 2 open 3. proper 4. hates 5waste 6. lend 7. communicate8. offers 9. return 10. nervous 11. perhaps 12. writing 13. imagine 14. not to wear 15. successful 16. themselves 17. typical 18. relations 19. arrives 20. whatever二.单项选择:1---5. BCBDC 6---10. CDBCC 11---15. BBCDA 16---20. BDABA。
人教版高中数学高二选修2-2课时作业1-2导数的计算
课时作业2 导数的计算一、选择题1.若对任意x 属于R ,f ′(x )=4x 3,f (1)=-1,则f (x )是( )A .f (x )=x 4B .f (x )=x 4-2C .f (x )=4x 3-5D .f (x )=x 4+2设f (x )=x 4+b ,∵f (1)=-1,∴b =-2,∴f (x )=x 4-2.故应选B.B2.函数y =12(e x +e -x )的导数是( ) A.12(e x -e -x ) B.12(e x +e -x ) C .e x -e -x D .e x +e -xy ′=⎣⎢⎡⎦⎥⎤12(e x +e -x )′=12(e x -e -x ). 故应选A.A3.若函数y =x 2+a 2x (a >0)的导数为0,则实数x 是( )A .aB .±aC .-aD .a 2y ′=⎝ ⎛⎭⎪⎪⎫x 2+a 2x ′=2x ·x -(x 2+a 2)x 2=x 2-a 2x 2,由x 2-a 2=0得x =±a .故应选B.B4.函数f (x )=2a 3+5a 2x 2-x 6的导数为( )A .6a 2+10ax 2-x 6B .2a 3+10a 2x -6x 5C .10a 2x -6x 5D .5a 2x -6x 5f ′(x )=(2a 3+5a 2x 2-x 6)′=10a 2x -6x 5.故应选C.C5.下列函数在x =0处没有切线的是( )A .y =3x 2+cos xB .y =x sin xC .y =1x +2xD .y =1cos x∵y ′=⎝ ⎛⎭⎪⎫1x +2x ′=⎝ ⎛⎭⎪⎫1x ′+(2x )′=-1x 2+2, ∴当x =0时,函数无定义,且y ′不存在,故该函数在x =0处没有切线.故应选C.C6.若曲线y =x n 在x =2处的导数为12,则n =( )A .1B .2C .3D .4y ′=(x n )′=n ·x n -1.由n ·2n -1=12得n =3.故应选C.C7.已知函数f (x )在x =1处的导数为3,则f (x )的解析式可能为( )A .f (x )=(x -1)3+3(x -1)B .f (x )=2(x -1)C .f (x )=2(x -1)2D .f (x )=x -1f (x )=(x -1)3+3(x -1),∵f ′(x )=3(x -1)2+3,∴f ′(1)=3.故应选A.A8.设函数y =f (x )是线性函数,已知f (0)=1,f (1)=-3,则f ′(x )=( )A .4xB .-4C .-2D .6由f (x )是线性函数,可设f (x )=ax +b (a ,b 为常数,且a ≠0),由f (0)=1,f (1)=-3,解得a =-4,b =1,∴f (x )=-4x +1,∴f ′(x )=-4.故应选B.B二、填空题9.曲线y =4x 3在点Q (16,8)处的切线的斜率是________.∵y =x 34 ,∴y ′=34x 34 -1 =34x -14 , ∴y ′| x =16=38.3810.曲线y =x 3+x +1在点(1,3)处的切线方程是________.令f (x )=x 3+x +1,由导数的几何意义知在点(1,3)处的切线斜率k =f ′(1)=3×12+1=4.所以由点斜式得切线方程为y -3=4(x -1),即4x -y -1=0.4x -y -1=1011.曲线y =x 3在点(1,1)处的切线与x 轴、直线x =2所围成的三角形的面积为________.y ′=3x 2,所以k =y ′⎪⎪x =1=3,所以切线方程为y -1=3(x -1),即y =3x -2.由⎩⎨⎧ y =3x -2x =2,解得⎩⎨⎧ x =2y =4,所以S =12×43×4=83. 83 12.曲线y =x 3在点(a ,a 3)(a ≠0)处的切线与x 轴、直线x =a 所围成的三角形的面积为16,则a =________. y ′=3x 2,所以切线方程为y -a 3=3a 2(x -a ),即y =3a 2x -2a 3.可求得切线与x 轴的交点为⎝ ⎛⎭⎪⎫23a ,0,与直线x =a 的交点为(a ,a 3),所以三角形面积为S =12×a 3×a 3=16,解得a =±1. ±1三、解答题13.已知抛物线y =ax 2+bx +c 通过点P (1,1),且在点Q (2,-1)处与直线y =x -3相切,求实数a ,b ,c 的值.∵曲线y =ax 2+bx +c 过点P (1,1),∴a +b +c =1. ① ∵y ′=2ax +b ,∴y ′|x =2=4a +b ,∴4a +b =1. ②又曲线过点Q (2,-1),∴4a +2b +c =-1. ③ 联立①②③解得a =3,b =-11,c =9.14.(1)求曲线y =2x x 2+1在点(1,1)处的切线方程; (2)运动曲线方程为S =t -1t 2+2t 2,求t =3时的速度. (1)∵y ′=2(x 2+1)-2x ·2x (x 2+1)2 =2-2x 2(x 2+1)2,y ′| x =1=2-24=0, 即曲线在点(1,1)处的切线斜率k =0,因此曲线y =2x x 2+1在(1,1)处的切线方程为y =1.(2)S ′=⎝ ⎛⎭⎪⎪⎫t -1t 2′+(2t 2)′ =t 2-2t (t -1)t 4+4t=-1t 2+2t 3+4t . S ′| t =3=-19+227+12=112627. 15.已知函数f (x )=ax 4+bx 3+cx 2+dx +e 为偶函数,它的图象过点A (0,-1),且在x =1处的切线方程为2x +y -2=0,求函数y =f (x )的表达式.∵f (x )是偶函数,f (-x )=f (x ),∴b =d =0,f (x )=ax 4+cx 2+e ,又∵图象过点A (0,-1),∴e =-1,∴f (x )=ax 4+cx 2-1,f ′(x )=4ax 3+2cx ,当x =1时,f ′(1)=4a +2c =-2, ①对于2x +y -2=0,当x =1时,y =0.∴点(1,0)在f (x )图象上,∴a +c -1=0. ②由①②解得a =-2,c =3,因此f (x )=-2x 4+3x 2-1.16.已知曲线C 1:y =x 2与C 2:y =-(x -2)2,直线l 与C 1,C 2都相切,求直线l 的方程.设l 与C 1相切于点P (x 1,x 21),与C 2相切于点Q (x 2,-(x 2-2)2).对C 1:y ′=2x ,则与C 1相切于点P 的切线方程为y -x 21=2x 1(x-x 1),即y =2x 1x -x 21. ①对C 2:y ′=-2(x -2),则与C 2相切于点Q 的切线方程为y +(x 2-2)2=-2(x 2-2)(x -x 2),即y =-2(x 2-2)x +x 22-4.② ∵两切线重合,∴⎩⎨⎧ 2x 1=-2(x 2-2)-x 21=x 22-4,解得⎩⎨⎧ x 1=0x 2=2或⎩⎨⎧ x 1=2x 2=0,∴直线方程为y =0或y =4x -4.。
人教版数学高二-课时作业 2-1第1课时 数列的概念与通项公式
第2章 2.1 第1课时(本栏目内容,在学生用书中以活页形式分册装订!)一、选择题(每小题5分,共20分)1.已知数列的通项公式:a n =⎩⎪⎨⎪⎧3n +1n 为奇数,2n -2n 为偶数,则a 2·a 3等于( )A .70B .28C .20D .8解析: a 2=2 2-2=2a 3=3 3+1=10 a 2·a 3=20.故选C.答案: C2.已知a n =n 2+n ,那么( ) A .0是数列中的项 B .20是数列中的项 C .3是数列中的项D .930不是数列中的项解析: 令n 2+n =0,得n =0或n =-1,∵n ∉N *,故A 错. 令n 2+n =20,即n 2+n -20=0,∴n =4或n =-5(舍), ∴a 4=20.故B 正确. 令n 2+n =3,即n 2+n -3=0.∴Δ=1-4 (-3)=13,故无有理根,C 错. 令n 2+n =930,即(n +31)(n -30)=0, ∴n =30或n =-31(舍),∴a 30=930,故D 错. 答案: B3.设数列2,5,22,11,⑤则25是这个数列的( ) A .第6项 B .第7项 C .第8项D .第9项解析: 该数列通项公式为a n =3n -1. 令3n -1=25,得n =7. 答案: B4.数列-1,43,-95,167,⑤的一个通项公式是( )A .a n =(-1)nn 22n -1B .a n =(-1)nn n +12n -1C .a n =(-1)nn 22n +1D .a n =(-1)nn 3-2n2n -1解析: 分子为1、4、9、16、⑤、n 2.分母为1、3、5、7、⑤、(2n -1),又奇数项为负,偶数项为正,故选A.答案: A二、填空题(每小题5分,共10分)5.数列35,12,511,37,⑤的一个通项公式是________.解析: 数列可写为:35,48,511,614,⑤,分子满足:3=1+2,4=2+2,5=3+2,6=4+2,⑤,分母满足:5=3 1+2,8=3 2+2,11=3 3+2,14=3 4+2,⑤,故通项公式为a n =n +23n +2.答案:n +23n +26.在数列-1,0,19,18,⑤,n -2n2,⑤中,0.08是它的第______项.解析: 令n -2n2=0.08,得2n 2-25n +50=0, 即(2n -5)(n -10)=0. 解得n =10或n =52(舍).∴a 10=0.08. 答案: 10三、解答题(每小题10分,共20分)7.已知有限数列45,910,1617,2526,⑤,m 2m 2+1(m ♏7).(1)指出这个数列的一个通项公式;(2)判断0.98是不是这个数列中的项?若是,是第几项? 解析: (1)由观察知数列的通项公式不是m 2m 2+1.又∵数列的分子依次为4,9,16,25,⑤可看成与项数n 的关系式为(n +1)2,而每一项的分母恰好比分子大1,∴通项公式的分母可以为(n +1)2+1. ∴数列的一个通项公式为a n =n +12n +12+1(n =1,2,⑤,m -1).(2)由(1)知数列的通项公式a n =n +12n +12+1,不妨设0.98是这个数列的第n 项,即n +12n +12+1=0.98,解得n =6∈N *, ∴0.98是数列中的第6项.8.已知数列{a n }的通项公式为a n =n 2-5n +4. (1)数列中有多少项是负数?(2)n 为何值时,a n 有最小值?并求出最小值. 解析: (1)由n 2-5n +4<0,解得1<n <4. ∵n ∈N *,∴n =2,3. ∴数列有两项是负数.(2)方法一:∵a n =n 2-5n +4=⎝ ⎛⎭⎪⎫n -522-94,可知对称轴方程为n =52=2.5.又因n ∈N *,故n =2或3时,a n 有最小值,其最小值为 22-5 2+4=-2. 方法二:设第n 项最小,由⎩⎪⎨⎪⎧a n ♎a n +1,a n ♎a n -1,得⎩⎪⎨⎪⎧n 2-5n +4♎n +12-5n +1+4,n 2-5n +4♎n -12-5n -1+4.解这个不等式组得2♎n ♎3, ∴n =2,3, ∴a 2=a 3且最小,∴a 2=a 3=22-5 2+4=-2. 尖子生题库☆☆☆9.(10分)如图所示,有n (n ♏2)行(n +1)列的士兵方阵:(1)写出一个数列,用它表示当n分别为2,3,4,5,6,⑤时方阵中的士兵人数;(2)说出(1)中数列的第5,6项,用a5,a6表示;(3)若把(1)中的数列记为{a n},求该数列的通项公式a n;(4)求a10,并说明a10所表示的实际意义.解析:(1)当n=2时,表示士兵的人数为2行3列,人数为6;当n=3时,表示3行4列,人数为12,依此类推,故所求数列为6,12,20,30,⑤.(2)方阵的行数比数列的序号大1,因此第5项表示的是6行7列,第6项表示的是7行8列,故a5=42,a6=56.(3)根据对数列的前几项的观察,归纳、猜想数列的通项公式.项:6=2 3,12=3 4,20=4 5,30=5 6❽❽❽❽序号: 1 23 4因此a n=(n+1)(n+2).(4)由(3)知a10=11 12=132,a10表示11行12列的士兵方阵中士兵的人数.。
初中七年级 课时作业 第2章自我评价
7.请结合显微镜操作要领,回答下列问题。
(1)现有甲、乙两台显微镜(甲:目镜10×,物镜40×;乙:目镜5×,物镜10×), 若要在视野中看到较多的细胞,应选择镜头组合是__乙____的显微镜。 (2)正常情况下在用显微镜观察时,眼睛和镜筒的相关位置应该是图1中的___D___ 。 (3)若观察到的物细像准较焦模螺糊旋,但视野亮度正常,要使物像更加清晰,可略微转动显 微镜的结构是_______________。
3.下列有关细胞结构的叙述,错误的是( D ) A.细胞的基本结构包括细胞膜、细胞质和细胞核 B.细胞膜对进出细胞的物质有一定的控制作用 C.细胞中的遗传信息主要储存于细胞核中 D.动、植物细胞结构根本的差异是动物细胞没有液泡和叶绿体
4.右图是根据动物特征进行归类的示意图。下列选项分别表示甲、乙、丙、丁四 类动物的归类依据,其中不正确的是( C )
(4)小枫在显微镜视野中找到了一个细胞(如图2),如要把它移到视野中央,应将载 物台上的装片往____←____(填“←”“↑”“→”或“↓”)方向移动。 (5)某同学在观察“口腔上皮细胞临时装片”时,发现视野中细胞有流动现象。请 你帮他想一个补救的办法:_拿__吸__水__纸__吸__去__过__多__的__溶__液_______。 (6)用显微镜观察临时装片时,你在下列哪种细胞中没有看到叶绿体?___A___。 A.洋葱鳞片叶内表皮细胞 B.黄瓜表层果肉细胞 C.黑藻叶片细胞 D.菠菜叶肉细胞 (7)植物细胞与动物细胞结构的主要不同点是植物细胞结构有 _叶__绿__体__、__细__胞__壁__、__液__泡___。 (8)细胞中能控制物质进出的结构是_细__胞__膜____。
10.下图所示是同学们非常熟悉的五类动物,它们与我们人类的生活密切相关, 有些是我们人类的好朋友。请根据已学的知识和生活常识回答下列问题。
2021-2022学年新教材人教A版数学必修第一册课时作业:2
课时作业(十二) 基本不等式[练基础]1.不等式a 2+1≥2a 中等号成立的条件是( ) A .a =±1 B .a =1 C .a =-1 D .a =0 2.若a ≥0,b ≥0且a +b =2,则( )A .ab ≤12B .ab ≥12C .a 2+b 2≥2D .a 2+b 2≤33.“a ,b 为正数”是“a +b >2ab ”的( ) A .充分不必要条件 B .必要不充分条件 C .充要条件D .既不充分也不必要条件4.设x >0,则y =3-3x -1x的最大值是( )A .3B .3-22C .3-23D .-15.已知x >0,y >0,且2x +y =1,则xy 的最大值是( ) A.14B .4C.18D .8 6.(多选)设a ,b ∈R ,则下列不等式一定成立的是( )A .a 2+b 2≥2abB .a +1a ≥2C .b 2+1≥2b D.⎪⎪⎪⎪b a +⎪⎪⎪⎪a b ≥27.若a <1,则a +1a -1与-1的大小关系是________.8.已知正数x ,y 满足x +2y =2,则1y +8x 的最小值为________.9.已知a >b >c ,你能比较出4与⎝⎛⎭⎫1a -b +1b -c (a -c )的大小吗?10.(1)若x <3,求y =2x +1+1x -3的最大值;(2)已知x >0,求y =2xx 2+1的最大值.[提能力]11.(多选)下列命题中正确的是( )A .y =x +1x ()x <0的最大值是-2B .y =x 2+3x 2+2的最小值是2C .y =2-3x -4x ()x >0的最大值是2-4 3D .y =x +4x -1()x >1最小值是5 12.(多选)下列结论正确的是( )A .若x <0,则y =x +1x的最大值为-2B .若a >0,b >0,则ab ≤⎝⎛⎭⎫a +b 22C .若a >0,b >0,且a +4b =1,则1a +1b的最大值为9D .若x ∈[]0,2,则y =x 4-x 2的最大值为213.已知x >0,y >0,且x +2y =3,则xy 的最大值为________,3x +yxy的最小值为________.14.已知5x 2y 2+y 4=1()x ,y ∈R ,则x 2+2y 2的最小值是________.15.已知正常数a ,b 和正变数x ,y 满足a +b =10,a x +by=1,x +y 的最小值为18,求a ,b 的值.[培优生]16.《几何原本》中的几何代数法(以几何方法研究代数问题)成了后世数学家处理问题的重要依据.通过这一原理,很多的代数的公理或定理都能够通过图形实现证明,也称之为无字证明.如图,在AB 上取一点C ,使得AC =a ,BC =b ,过点C 作CD ⊥AB 交半圆周于点D ,连接OD .作CE ⊥OD 交OD 于点E .由CD ≥DE 可以直接证明的不等式为( )A.ab ≥2aba +b(a >0,b >0)B.a +b 2≥ab (a >0,b >0)C.a 2+b 22≥a +b 2(a >0,b >0)D .a 2+b 2≥2ab (a >0,b >0)课时作业(十二) 基本不等式1.解析:当a 2+1=2a ,即(a -1)2=0, 即a =1时,等号成立.故选B. 答案:B2.解析:因为a 2+b 2≥2ab ,所以(a 2+b 2)+(a 2+b 2)≥(a 2+b 2)+2ab , 即2(a 2+b 2)≥(a +b )2=4,所以a 2+b 2≥2.故选C. 答案:C3.解析:若a ,b 为正数,取a =1,b =1,则a +b =2ab ,则“a ,b 为正数”不是“a +b >2ab ”的充分条件;若a +b >2ab ,取a =1,b =0,则b 不是正数,则“a ,b 为正数”不是“a +b >2ab ”的必要条件.故“a ,b 为正数”是“a +b >2ab ”的既不充分也不必要条件.故选D.答案:D4.解析:y =3-3x -1x =3-⎝⎛⎭⎫3x +1x ≤3-23x ·1x =3-23,当且仅当3x =1x ,即x =33时取等号.故选C.答案:C5.解析:由题意得,xy =12×2xy ≤12×⎝⎛⎭⎫2x +y 22=12×⎝⎛⎭⎫122=18,当且仅当x =14,y =12时等号成立,所以xy 的最大值是18.故选C.答案:C6.解析:当a ,b ∈R 时,a 2+b 2≥2ab 成立,故A 正确;当a >0时,a +1a≥2,等号成立的条件是a =1,当a <0时,a +1a≤-2,等号成立的条件是a =-1,故B 不正确;当b ∈R 时,b 2+1-2b =(b -1)2≥0,所以b 2+1≥2b ,故C 正确;⎪⎪⎪⎪b a >0,⎪⎪⎪⎪a b >0,所以⎪⎪⎪⎪b a +⎪⎪⎪⎪a b ≥2⎪⎪⎪⎪b a ×⎪⎪⎪⎪a b =2,等号成立的条件是当且仅当⎪⎪⎪⎪b a =⎪⎪⎪⎪a b ,即a 2=b 2时,故D 正确.故选ACD.答案:ACD7.解析:因为a <1,即1-a >0,所以-⎝⎛⎭⎫a -1+1a -1=(1-a )+11-a ≥2(1-a )·11-a=2.即a +1a -1≤-1. 答案:a +1a -1≤-18.解析:因为x >0,y >0且x +2y =2,所以1y +8x =x +2y 2y +4x +8yx=5+x 2y +8y x ≥5+2x 2y ·8y x =9(当且仅当x 2y =8y x ,即x =4y =43时取等号),即1y +8x的最小值为9.答案:99.解析:⎝⎛⎭⎫1a -b +1b -c (a -c )≥4,理由如下:因为a -c =(a -b )+(b -c ),所以⎝⎛⎭⎫1a -b +1b -c [(a -b )+(b -c )]=2+b -c a -b +a -b b -c,又a >b >c ,所以b -c a -b +a -bb -c≥2,故⎝⎛⎭⎫1a -b +1b -c (a -c )≥4, 当且仅当b -c a -b =a -bb -c时,取“=”.10.解析:(1)因为x <3,所以3-x >0.又因为y =2(x -3)+1x -3+7=-⎣⎡⎦⎤2(3-x )+13-x +7,由基本不等式可得2(3-x )+13-x ≥22(3-x )·13-x =22,当且仅当2(3-x )=13-x,即x =3-22时,等号成立,于是-⎣⎡⎦⎤2(3-x )+13-x ≤-22,-⎣⎡⎦⎤2(3-x )+13-x +7≤7-22,故y 的最大值是7-2 2.(2)y =2x x 2+1=2x +1x.因为x >0,所以x +1x ≥2x ·1x =2,所以0<y ≤22=1,当且仅当x=1x,即x =1时,等号成立.故y 的最大值为1. 11.解析:对于A ,y =x +1x =-⎝⎛⎭⎫-x -1x ≤-2-x ·⎝⎛⎭⎫-1x =-2,当且仅当-x =-1x,即x =-1时,等号成立,所以y =x +1x ()x <0的最大值是-2,故A 正确;对于B ,y =x 2+3x 2+2=x 2+2+1x 2+2>2,因为x 2+2=1x 2+2,即x 2+2=1无解,即等号不成立,所以y =x 2+3x 2+2取不到最小值2,故B 错误;对于C ,y =2-3x -4x (x >0)=2-(3x +4x )≤2-23x ·4x =2-43,当且仅当3x =4x ,即x =233时,等号成立,所以y =2-3x -4x(x >0)的最大值是2-43,故C 正确;对于D ,y =x +4x -1=x -1+4x -1+1≥2()x -1·4x -1+1=5,当且仅当x -1=4x -1,即x =3时,等号成立,所以y =x +4x -1()x >1最小值是5,故D 正确;故选ACD.答案:ACD12.解析:A 选项,由x <0可得y =x +1x =-⎣⎡⎦⎤()-x +⎝⎛⎭⎫-1x ≤-2()-x ·⎝⎛⎭⎫-1x =-2,当且仅当-x =-1x,即x =-1时,等号成立;即y =x +1x 的最大值为-2;A 正确;B 选项,由a >0,b >0,可得⎝⎛⎭⎫a +b 22-ab =a 2+b 2-2ab 4=⎝⎛⎭⎫a -b 22≥0,即ab ≤⎝⎛⎭⎫a +b 22,故B 正确;C 选项,若a >0,b >0,且a +4b =1,则1a +1b =⎝⎛⎭⎫1a +1b ()a +4b =1+4b a +a b +4≥5+24b a ·a b =9,当且仅当4b a =a b ,即⎩⎨⎧a =13b =16时,等号成立;即1a +1b 的最小值为9,故C 错;D 选项,因为0≤x ≤2,所以y =x4-x 2≤x 2+()4-x 22=2,当且仅当x =4-x 2,即x =2时,等号成立,故D 正确.故选ABD.答案:ABD13.解析:∵x >0,y >0∴x +2y =3≥22xy ,解之得:xy ≤98.当且仅当x =2y ,即x =32,y =34时,等号成立.∴xy 的最大值为98.3x +y xy =3y +1x =13()x +2y ⎝⎛⎭⎫3y +1x =73+13⎝⎛⎭⎫3x y +2y x ≥73+233x y ·2y x =7+263.当且仅当3x y =2yx ,即x =36-35,y =18-3610时,等号成立.∴3x +y xy 的最小值为7+263.另解:∵x >0,y >0,且x +2y =3∴x =3-2y >0,∴0<y <32.∴xy =y ()3-2y =-2y 2+3y =-2⎝⎛⎭⎫y -342+98. ∵0<y <32,∴当y =34时,()xy max =98,此时x =32.答案:98 7+26314.解析:∵5x 2y 2+y 4=1∴y ≠0且x 2=1-y 45y 2∴x 2+2y 2=1-y 45y 2+2y 2=15y 2+9y 25≥215y 2·9y 25=65,当且仅当15y 2=9y 25,即x 2=815,y 2=13时取等号.∴x 2+y 2的最小值为65.答案:6515.解析:因为x +y =(x +y )·1=(x +y )·⎝⎛⎭⎫a x +b y =a +b +ay x +bxy ≥a +b +2ab =(a +b )2,当且仅当ay x =bxy,即y x =b a时,等号成立, 所以x +y 的最小值为(a +b )2=18, 又a +b =10,所以ab =16.所以a ,b 是方程x 2-10x +16=0的两根, 所以a =2,b =8或a =8,b =2. 16.解析:由三角形相似,知CD 2=DE ·OD =AC ·BC ,即DE =DC 2OD =ab a +b 2=2aba +b,由CD ≥DE ,得ab ≥2aba +b,故选A.答案:A。
2019_2020学年新教材高中英语Unit4FriendsforeverPeriod2课时作业(二)外研版必修第一册
Period 2 Understanding ideas课时作业(二)[基础训练]Ⅰ单词拼写1.I am going to buy a ________ (数字的) camera for my friend who likes taking photos.答案:digital2.Leaflets have been ________ (递送) to every household.答案:delivered3.I would ________ (更喜欢) it if you didn't tell anyone.答案:prefer4.My old friend Jack and I have always ________ (保持,维持) close relations.答案:maintained5.I have a good command of oral English, which ________ (使能够) me to hold the position.答案:enablesⅡ单句语法填空1.It's cheaper if you book the tickets ________ advance.答案:in in advance固定短语,意为“提前,预先”。
2.It must be kept ________ mind that there is no secret of success but hard work.答案:in keep ... in mind固定短语,意为“牢记”。
3.The number of local people now supporting him has increased ________ (significant).答案:significantly 所填词修饰句子的谓语动词has increased,应用副词,故填significantly。
湘教版数学九年级上册_课时作业:第2课时_图形面积和动点问题
2.5第2课时图形面积和动点问题一、选择题1.王叔叔从市场上买了一块长80 cm、宽70 cm的矩形铁皮,准备制作一个工具箱.如图,他将矩形铁皮的四个角各剪掉一个边长为x cm的正方形后,剩余的部分刚好能围成一个底面积为3000 cm2的无盖长方体工具箱,根据题意可列方程为()A.(80-x)(70-x)=3000B.80×70-4x2=3000C.(80-2x)(70-2x)=3000D.80×70-4x2-(70+80)x=30002.如图,在宽为20米,长为30米的矩形地面上修建两条同样宽的道路,余下部分作为耕地.若耕地面积需要551平方米,则修建的路宽应为()A.1米B.1.5米C.2米D.2.5米3.如图,将边长为2 cm的正方形ABCD沿其对角线AC剪开,再把△ABC沿着AD方向平移,得到△A′B′C′.若两个三角形重叠部分的面积为 1 cm2,则它移动的距离AA′的值为()A.0.5 cm B.1 cm C.1.5 cm D.2 cm4.如图,在△ABC中,AC=50 cm,BC=40 cm,∠C=90°,点P从点A开始沿AC边向点C以2 cm/s的速度匀速移动,同时另一点Q由点C开始以3 cm/s的速度沿着射线CB 匀速移动,当△PCQ的面积等于300 cm2时,运动时间为()A.5 s B.20 s C.5 s或20 s D.不确定二、填空题5.如图,用长度为32米的篱笆,一面利用墙(墙的最大可用长度为16米),围成一个面积为120平方米的长方形花圃.若设BC的长为x米,则根据条件能得到一个关于x的一元二次方程,该方程的一般形式为______________.(不用写出x的取值范围)6.如图所示,在Rt△ABC中,∠BAC=90°,AB=AC=16 cm,AD为BC边上的高,动点P从点A出发,沿AD方向以 2 cm/s的速度向点D运动.E为AC边上一点.设△ABP 的面积为S1,矩形PDFE的面积为S2,运动时间为t s,则t=________时,S1=2S2.三、解答题7.如图①,要设计一幅宽20 cm、长30 cm的矩形图案,其中有两横两竖的彩条,横、竖彩条的宽度比为2∶3.如果要使所有彩条所占面积为原矩形图案面积的三分之一,应如何设计每个彩条的宽度?分析:由横、竖彩条的宽度比为2∶3,可设每个横彩条的宽为2x cm,则每个竖彩条的宽为3x cm.为更好地寻找题目中的等量关系,将横、竖彩条分别集中,原问题转化为如图②的情况,得到矩形ABCD.(1)如图②,用含x的代数式表示:AB=________cm,AD=________cm,矩形ABCD的面积为_______________cm2;(2)列出方程并完成本题解答.8.图是一幅长20 cm 、宽12 cm 的图案,其中有一横两竖的彩条,横、竖彩条的宽度比为3∶2.设竖彩条的宽度为x cm ,图案中三条彩条所占面积为y cm 2.(1)试用含有x 的代数式表示y ,并确定x 的取值范围;(2)若图案中三条彩条所占面积是图案面积的25,求横、竖彩条的宽度.9.如图,在△ABC 中,∠B =90°,AB =6 cm ,BC =3 cm ,点P 从点A 开始沿AB 边向点B 以2 cm/s 的速度移动,点Q 从点B 开始沿BC 边向点C 以1 cm/s 的速度移动,如果P ,Q 两点同时出发,点P 运动到C 时,P ,Q 两点同时停止运动.(1)几秒钟后,△APQ 是等腰三角形?(2)几秒钟后,△BPQ 的面积是四边形CQP A 的面积的1310.李明准备进行如下试验操作:把一根长40 cm 的铁丝剪成两段,并把每段首尾相连各围成一个正方形.(1)要使这两个正方形的面积之和等于58 cm 2,李明应该怎么剪这根铁丝?(2)李明认为这两个正方形的面积之和不可能等于48 cm 2,你觉得他的想法正确吗?请说明理由.方案设计某小区计划在一块长100 m 、宽60 m 的矩形荒地上修建一个配绿化带的活动区,要求整体布局既是轴对称图形,又是中心对称图形,且绿化率不低于35%(绿化率=绿化面积总面积×100%).(1)甲方案:如图①所示,设计两条互相垂直且宽度都为a m 的十字活动区域,周边四块为绿化带(图中阴影部分),若绿化面积为2100 m 2,求a 的值;(2)乙方案:如图K -16-10②所示(单位:m),场地正中央设计菱形绿化带(图中阴影部分),周边为活动区域,请通过计算说明该方案是否符合要求.详解详析[课堂达标] 1.[答案] C2.[解析] A 设修建的路宽为x m .依题意,得(30-x)(20-x)=551, 解得x 1=1,x 2=49(不合题意,舍去).3.[解析] B 设AC 交A′B′于点H.∵∠A =45°,∠AA′H =90°,∴△A′HA 是等腰直角三角形.设AA′=x cm ,则阴影部分的底A′H 的长为x cm ,高A′D =(2-x)cm ,∴x·(2-x)=1,∴x 1=x 2=1,即AA′=1 cm .4.[解析] C 设运动时间为t s ,则AP =2t ,CQ =3t ,∴PC =50-2t.∵12·PC·CQ =300,∴12·(50-2t)·3t =300,解得t =20或t =5,∴运动时间为20 s 或5 s 时,△PCQ 的面积等于300 cm 2.故选C .5.[答案] x 2-32x +240=0[解析] 依题意得12(32-x)x =120.整理,得x 2-32x +240=0.6.[答案] 6[解析] ∵在Rt △ABC 中,∠BAC =90°,AB =AC =16 cm ,AD 为BC 边上的高, ∴AD =BD =CD =8 2 cm .又∵AP =2t cm ,则S 1=12AP·BD =12×2×8 2t =8t ,PD =(8 2-2t)cm .∵PE ∥BC ,∴∠AEP =∠C =45°,∠APE =∠ADC =90°, ∴∠PAE =∠AEP =45°,∴PE =AP =2t cm ,∴S 2=PD·PE =(8 2-2t)·2t.∵S 1=2S 2,∴8t =2(8 2-2t)·2t ,解得t =6或t =0(舍去).故答案是6.7.[解析] 读懂题中的分析,利用已有的数量关系与面积公式列方程. 解:(1)(20-6x)(30-4x) (20-6x)(30-4x) (2)根据题意,得(20-6x)(30-4x)=(1-13)×20×30.整理,得6x 2-65x +50=0,解得x 1=56,x 2=10(不合题意,舍去),则2x =53,3x =52.答:每个横、竖彩条的宽度分别为53 cm ,52 cm .8.解:(1)根据题意可知,横彩条的宽度为32x cm ,∴⎩⎪⎨⎪⎧x>0,20-2x>0,12-32x>0,解得0<x <8.y =20×32x +2×12·x -2×32x·x =-3x 2+54x ,即y =-3x 2+54x(0<x <8).(2)根据题意,得-3x 2+54x =25×20×12,整理,得x 2-18x +32=0, 解得x 1=2,x 2=16(舍去),∴32x =3.答:横彩条的宽度为3 cm ,竖彩条的宽度为2 cm . 9.解:设运动时间为t s ,则AP =2t ,BP =6-2t ,BQ =t. (1)∵∠B =90°,∴∠APQ >90°. ∵△APQ 是等腰三角形,∴AP =PQ ,即2t =(6-2t )2+t 2,解得t 1=12-6 3,t 2=12+6 3>3(不合题意,舍去).答:(12-6 3)s 后,△APQ 是等腰三角形.(2)△BPQ 的面积是四边形CQPA 的面积的13,即△BPQ 的面积等于△ABC 面积的14.∵S △BPQ =12BP·BQ =12(6-2t)t =3t -t 2,S △ABC =12AB·BC =9,∴3t -t 2=94,即t 2-3t +94=0,解得t 1=t 2=32.答:32s 后,△BPQ 的面积是四边形CQPA 的面积的13.11.解:(1)设剪成的较短的铁丝长为x cm ,则较长的铁丝长为(40-x)cm . 由题意,得⎝⎛⎭⎫x 42+⎝⎛⎭⎫40-x 42=58, 解得x 1=12,x 2=28, 当x =12时,40-12=28(cm ),当x =28时,40-28=12(cm )<28 cm (舍去).答:李明应该把铁丝剪成12 cm 和28 cm 的两段.(2)正确.理由:设剪成的较短的铁丝长为m cm ,则较长的铁丝长为(40-m)cm , 由题意,得⎝⎛⎭⎫m 42+⎝⎛⎭⎫40-m 42=48. 整理,得m 2-40m +416=0. ∵Δ=(-40)2-4×416=-64<0, ∴原方程无实数根,∴这两个正方形的面积之和不可能等于48 cm 2,即李明的想法正确. [素养提升]解:(1)依题意有(100-a)(60-a)=2100, 解得a 1=30,a 2=130(不合题意,舍去). 答:a 的值是30.(2)100-5×2=100-10=90(m ), 60-5×2=60-10=50(m ), 90×50÷2=2250(m 2), 100×60=6000(m 2), 22506000×100%=37.5%. ∵37.5%>35%, ∴该方案符合要求.。
高中英语课时作业二Unit1ANewStartSectionⅡUsinglangua外研版必修第一册
课时作业(二) Unit 1 Section Ⅱ Using language 语言知识训练Ⅰ.单词拼写1.I've heard that you are a talented young woman, and I have found you charming and i________ (聪明的) as well.2.T o get the most out of reading these plays, try to picture the play on s________ (舞台), with you, the reader, in the audience.3.Y ou can be the one who directs the conversation to fun t________ (话题) that are ripe for others to add humor.4.If you take the trouble to s________ (安排) a visit, you can be more or less guaranteed of a response.5.The musician along with his b________ (乐队) members has given ten performances in the last three months.6.Unlike traditional gyms, appbacked g________ (健身房) offer people flexible options to exercise.7.Being very interested in your English drama club when I saw your p________ (海报), I would like to join the big family.8.I am so glad to have the chance to join the d________ (讨论). Now I want to say something about garbage classification.9.I'm more than glad to have been invited to attend the p________ (钢琴) concert with you.10.When he heard these words, my father felt his i________ (内心的) doubts melt away.Ⅱ.请选用所给短语的适当形式填空look after, play a part in, argue about, come along, care about, such as, twice a month, take part in1.For 10 years she ____________ her three children with her career very much on the back burner.2.He and his sister always ____________ politics.3.I'm so stupid. I shouldn't have ____________ with you to this place.4.He goes backwards and forwards between Dalian and Shanghai ____________.5.His toes are hurt and he is unable to ____________ today's basketball game.6.He bought a lot of fruit ____________ apples and peaches.7.The famous writer neither worried nor ____________ public opinion.8.The agriculture during the19th century____________the early industrialization of the United States.Ⅲ.单句语法填空1.The street was crowded with reporters, ________ (photograph), cameras and microphones.2.It's ________ (argue) whether the plan is actually worthwhile.3.The pencil case contains pencils, a pencil ________ (sharp) and an eraser.4.A workman must ________ (sharp) his tools if he is to do his work well.5.I believe that the science of artificial ________ (intelligent) is waiting for humanity to explore it step by step.6.Reading books is learning; ________ (apply) is also learning and the more important form of learning.7.It's not right to make a decision without ________ (investigate) and study.8.With the development of industry,people's material wealth and lifestyle changed ________ (drama) .9.In the UK and US, senior high school students take part in ________ (vary) afterschool activities.10.In the mid1990s,T om Bissell taught English as ________ volunteer in Uzbekistan.Ⅳ.写出下列句子的句型结构1.James is an exchange student.________________________________________________________________________ 2.Y ou should register before Friday.________________________________________________________________________ 3.The traffic light is flashing.________________________________________________________________________ 4.His words gave me more confidence.________________________________________________________________________ 5.I found her an outgoing and kind girl.________________________________________________________________________ 6.The boy was reading a story in a loud voice.________________________________________________________________________ 7.The designer designed a beautiful dress.________________________________________________________________________ 8.They argued fiercely.________________________________________________________________________ 9.The new student looks anxious and frightened.________________________________________________________________________ 10.Planting trees is important especially in mountainous areas.________________________________________________________________________ 语言能力训练Ⅰ.阅读理解Although toys'packaging says it's educational,it doesn't make it so. That's the finding from a new study in JAMA Pediatrics that found some toys being marketed as language promoters got in the way of learning.Research shows that for kids to understand, speak and eventually read or write a language, they need to hear it—lots of it. And it's never too early for parents and caregivers to get talking. That explains the fast industry in talking electronic toys that claim to help kids learn language.“We had a talking on farmanimal names and things,”Professor Anna Sosa says of the electronic toys. “We had a baby cell phone. And we had a baby laptop. So you open the cover and start pushing buttons, and it tells you things. The parentchild couples were asked to play separately with each type of toy over the course of three days.”“When there's something else that's doing some talking,the parents seem to be sitting on the sidelines and letting the toy talk for them and respond for them,” Sosa says. “That's bad because the best way a toy can promote language in babies and kids is by exciting interaction between parent and child. There's simply no evidence that a young child can learn language directly from a toy. It isn't responsive enough. It isn't social.”As for the other toys, traditional blocks and puzzles stimulated more conversation than the electronic toys,and books outscored them all. But don't underestimate the humble block. “While traditional toys fell short of books in interaction quantity,”Sosa notes, “they kept pace in terms of quality.”1.What is the finding of the research led by Professor Anna Sosa?A.The toy industry is facing new challenges in marketing.B.Kids should be taught to learn with toys as early as possible.C.People might be misled by the statements of some toy makers.D.Parents need to be cautious when choosing toys for their kids.2.According to the passage, why are talking electronic toys so popular?A.Because they represent the latest creations.B.Because they arouse the interest in learning.C.Because they are used as an educational tool.D.Because they are easy for the kids to control.3.What can we infer from the fourth paragraph?A.It is necessary for the parents to share their experiences of reading with their kids.B. It is necessary for the parents to spare more time to stay with their kidsat home.C.It is necessary for the parents to encourage their kids to attend social activities.D.It is necessary for the parents to get involved in the conversations with their kids.4.What is the author's attitude to electronic toys as language promoters?A.Critical. B.Doubtful.C.Supportive. D.Objective.Ⅱ.七选五How to Be a Good Listener in ClassBeing a good student means being a good listener.Whether you're a young student or entering college, it's important to learn to pay attention in class and take good notes, which will help you succeed.__1__.Be prepared for classWhen it's time to go to class, make sure you've got everything that you need ready to go,so you won't have to miss anything because you're struggling to catch up.__2__. In general, you want to make sure you have, for each class:notebooks,pencils already sharpened or pens that work well, books needed for class.Look at the teacher__3__.When your teacher is talking, your eyes should be to the front. Don't look out the window, or at the kids next to you, or at the phone you're trying to hide under your desk. Look at your teacher and what is being presented.__4__Concentrate on understanding the broad concepts, and don't try to catch every single word.Listen for key words and concepts that your teacher mentions, and pay attention to what's written on the board. Anything that the teacher takes the time to write down on the board is extremely important. Also, anything that is repeated several times is very important.T ake good notesHave a different notebook for each class, and have some pencils or pens ready to go when you want to take notes.__5__. It's not necessary to have a total record of everything your teacher says. As long as you try to keep up and write down important ideas, taking notes is a good way of paying attention in class.A.Listen to important ideasB.Remember what you hearC.Only write down key wordsD.Good listening starts with good watchingE.Have good notetaking materials ready to go while in classF.Learn to listen well and set yourself up for success by staying focused G.Y ou'll miss part of a lecture if you're trying to finish your homework before class starts课时作业(二)层级一 语言知识训练Ⅰ.单词拼写1.intelligent 2.stage 3.topics 4.schedule 5.band6.gyms 7.poster 8.debate 9.piano 10.innerⅡ.请选用所给短语的适当形式填空1.has looked after 2.argue about e along 4.twice a month 5.take part in 6.such as 7.cared about 8.played a part inⅢ.单句语法填空1.photographers 2.arguable 3.sharpener 4.sharpen 5.intelligence 6.application 7.investigation 8.dramatically 9.various 10.aⅣ.写出下列句子的句型结构1.JamesS __is__V an__exchange__student.P2.Y ouS should__registerV before__Friday.A3.The__traffic__lightS is__flashing.V4.His__wordsS gaveV me__IO more__confidence.DO5.IS foundV herO an__outgoing__and__kind__girl.OC6.The__boyS was__readingV a__storyO in__a__loud__voice.A7.The__designerS designedV a__beautiful__dress.O8.TheyS arguedV fiercely.A9.The__new__studentS looksV anxious__and__frightened.P10.Planting__treesS is__V importantP especially__in__mountainous__areas.A层级二 语言能力训练Ⅰ.阅读理解【语篇解读】 本文是一篇议论文。
2021-2022学年新教材人教A版数学必修第一册课时作业:2
课时作业(十五) 一元二次不等式的应用[练基础]1.不等式x +5(x -1)2≥2的解集是( ) A.⎩⎨⎧⎭⎬⎫x ⎪⎪ -3≤x ≤12 B.⎩⎨⎧⎭⎬⎫x ⎪⎪-12≤x ≤3 C.⎩⎨⎧⎭⎬⎫x ⎪⎪ 12≤x <1或1<x ≤3 D.⎩⎨⎧⎭⎬⎫x ⎪⎪-12≤x ≤3且x ≠1 2.若集合A ={x |ax 2-ax +1<0}=∅,则实数a 的取值范围是( )A .{a |0<a <4}B .{a |0≤a <4}C .{a |0<a ≤4}D .{a |0≤a ≤4}3.不等式2-x x +1<1的解集是( ) A .{x |x >1}B .{x |-1<x <2}C.⎩⎨⎧⎭⎬⎫x ⎪⎪ x <-1或x >12 D.⎩⎨⎧⎭⎬⎫x ⎪⎪-1<x <12 4.“t ≥-2”是“对任意正实数x ,都有t 2-t ≤x +1x恒成立”的 ( ) A .充分不必要条件B .必要不充分条件C .充要条件D .既不充分也不必要条件5.若不等式x 2-2x +5≥a 2-3a 对任意实数x 恒成立,则实数a 的取值范围为( )A .{a |-1≤a ≤4}B .{a |a ≤2或a ≥5}C .{a |a ≤-1或a ≥4}D .{a |-2≤a ≤5}6.(多选)下列结论错误的是( )A .若方程ax 2+bx +c =0(a ≠0)没有实数根,则不等式ax 2+bx +c >0的解集为RB .不等式ax 2+bx +c ≤0在R 上恒成立的条件是a <0且Δ=b 2-4ac ≤0C .若关于x 的不等式ax 2+x -1≤0的解集为R ,则a ≤-14D .不等式1x>1的解集为x <1 7.不等式x -1x>0的解集为________. 8.某小型雨衣厂生产某种雨衣,售价P (元/件)与月销售量x (件)之间的关系为P =160-2x ,生产x 件的成本R =500+30x .若每月获得的利润y 不少于1300元,则该厂的月销售量x 的取值范围为________.9.函数y =x 2+mx +m 2对一切x ∈R 恒成立,求实数m 的取值范围.10.第一机床厂投资A 生产线500万元,每万元可创造利润1.5万元.该厂通过引进先进技术,在A 生产线的投资减少了x (x >0)万元,且每万元创造的利润变为原来的(1+0.005x )倍.现将在A 生产线少投资x 万元全部投入B 生产线,且每万元创造的利润为1.5(a -0.013x )万元,其中a >0.(1)若技术改进后A 生产线的利润不低于原来A 生产线的利润,求x 的取值范围;(2)若B 生产线的利润始终不高于技术改进后A 生产线的利润,求a 的最大值.[提能力]11.(多选)若关于x 的一元二次方程(x -2)(x -3)=m 有实数根x 1,x 2,且x 1<x 2,则下列结论中正确的说法是( )A .当m =0时,x 1=2,x 2=3B .m >-14C .当m >0时,2<x 1<x 2<3D .当m >0时,x 1<2<3<x 212.对任意a ∈{a |-1≤a ≤1},函数y =x 2+(a -4)x +4-2a 的值恒大于零,则x 的取值范围是( )A .1<x <3B .x <1或x >3C .1<x <2D .x <1或x >213.要使不等式x 2+(a -6)x +9-3a >0,|a |≤1恒成立,则x 的取值范围为________.14.某辆汽车以x km/h 的速度在高速公路上匀速行驶(考虑到高速公路行车安全,要求60≤x ≤120)时,每小时的油耗(所需要的汽油量)为15(x -k +4500x)L ,其中k 为常数.若汽车以120km/h 的速度行驶时,每小时的油耗为11.5L ,则k =________,欲使每小时的油耗不.超过..9L ..,则速度x 的取值范围为________. 15.设函数y =ax 2+(b -2)x +3.(1)若不等式y >0的解集为{x |-1<x <1},求实数a ,b 的值;(2)若当x =1时y =0,且存在x ∈R ,使y >4成立,求实数a 的取值范围.[培优生]16.已知不等式x 2-8x +20(m 2-1)x 2+2(m +1)x -1<0,是否存在实数m ,使该不等式对于一切实数x 恒成立?如果存在,求出m 的取值范围;如果不存在,请说明理由.课时作业(十五) 一元二次不等式的应用1.解析:∵原不等式等价于⎩⎪⎨⎪⎧ x +5≥2(x -1)2,x ≠1, ∴⎩⎪⎨⎪⎧2x 2-5x -3≤0,x ≠1, ∴⎩⎪⎨⎪⎧ -12≤x ≤3,x ≠1,即⎩⎨⎧⎭⎬⎫x ⎪⎪-12≤x ≤3且x ≠1. 故选D.答案:D2.解析:当a =0时,满足条件.当a ≠0时,由⎩⎪⎨⎪⎧a >0,Δ=(-a )2-4a ≤0,得0<a ≤4.所以0≤a ≤4. 故选D.答案:D3.解析:原不等式等价于2-x x +1-1<0⇔1-2x x +1<0⇔(x +1)·(1-2x )<0⇔(2x -1)(x +1)>0,解得x <-1或x >12.故选C. 答案:C4.解析:由于x +1x≥2,可知t 2-t ≤2,解得-1≤t ≤2. 所以“t ≥-2”是“-1≤t ≤2”的必要不充分条件.故选B.答案:B5.解析:x 2-2x +5=(x -1)2+4的最小值为4,所以x 2-2x +5≥a 2-3a 对任意实数x 恒成立,只需a 2-3a ≤4,解得-1≤a ≤4.故选A.答案:A6.解析:A 选项中,只有a >0时才成立;B 选项当a =b =0,c ≤0时也成立;D 选项x 是大于0的.故选ABD.答案:ABD7.解析:x -1x>0同解于x (x -1)>0,解得:x <0或x >1 即原不等式的解集为{}x |x <0或x >1.答案:(-∞,0)∪(1,+∞)8.解析:由题意,得:y =Px -R =x (160-2x )-(500+30x )∴y =-2x 2+130x -500,令y ≥1300,得-2x 2+130x -500≥1300,∴x 2-65x +900≤0,∴(x -20)(x -45)≤0,∴20≤x ≤45.答案:20≤x ≤459.解析:由题意知x 2+mx +m 2≥0对一切x ∈R 恒成立,所以Δ=m 2-2m ≤0,所以0≤m ≤2.10.解析:(1)由题意,得1.5(1+0.005x )(500-x )≥1.5×500,整理得x 2-300x ≤0,解得0≤x ≤300,又x >0,故0<x ≤300.(2)由题意知,B 生产线的利润为1.5(a -0.013x )x 万元,技术改进后,A 生产线的利润为1.5(1+0.005x )(500-x )万元,则1.5(a -0.013x )x ≤1.5(1+0.005x )(500-x )恒成立,又x >0,∴a ≤x 125+500x +1.5恒成立,又x 125+500x≥4,当且仅当x =250时等号成立, ∴0<a ≤5.5,即a 的最大值为5.5.11.解析:A 中,m =0时,方程为(x -2)(x -3)=0,解为:x 1=2,x 2=3,所以A 正确; B 中,方程整理可得:x 2-5x +6-m =0,由不同两根的条件为:Δ=25-4(6-m )>0,可得m >-14,所以B 正确. 当m >0时,即(x -2)(x -3)>0,函数y =(x -2)(x -3)-m >0与x 轴的交点于(x 1,0),(x 2,0),如图可得x 1<2<3<x 2,所以D 正确,C 不正确;故选ABD.答案:ABD12.解析:设y =(x -2)a +(x 2-4x +4),y >0恒成立且-1≤a ≤1⇔⎩⎪⎨⎪⎧ 当a =1时,x 2-3x +2>0当a =-1时,x 2-5x +6>0⇔⎩⎪⎨⎪⎧x <1或x >2x <2或x >3 ⇔x <1或x >3.故选B.答案:B13.解析:x 2+(a -6)x +9-3a =[x +(a -3)](x -3)=0,解得x =3-a ,x =3.由|a |≤1⇒-1≤a ≤1,当0≤a ≤1,3-a <3,不等式[x +(a -3)](x -3)>0的解为x <3-a 或x >3由题意x <3-a 恒成立,故x <2.当-1≤a <0,3-a >3,不等式[x +(a -3)](x -3)>0的解为x >3-a 或x <3由题意x >3-a 恒成立,故x >4.综上所述:x <2或x >4.答案:x <2或x >414.解析:由题意,当x =120时,15⎝⎛⎭⎫x -k +4500x =11.5,所以k =100. 由15⎝⎛⎭⎫x -100+4500x ≤9,得x 2-145x +4500≤0, 所以45≤x ≤100.又因为60≤x ≤120,所以60≤x ≤100.答案:100 60≤x ≤10015.解析:(1)由题意可知:方程ax 2+(b -2)x +3=0的两根是-1,1所以⎩⎨⎧-b -2a =-1+1=03a =(-1)×1=-1解得⎩⎪⎨⎪⎧a =-3b =2 (2)当x =1时,y =0,得b =-a -1存在x ∈R ,y >4成立,即使ax 2+(b -2)x -1>0成立,又因为b =-a -1,代入上式可得ax 2-(a +3)x -1>0成立.当a ≥0时,显然存在x ∈R 使得上式成立;当a <0时,需使方程ax 2-(a +3)x -1=0有两个不相等的实根所以Δ=(a +3)2+4a >0即a 2+10a +9>0解得a <-9或-1<a <0综上可知a 的取值范围是a <-9或a >-1.16.解析:假设存在这样的m ,使不等式x 2-8x +20(m 2-1)x 2+2(m +1)x -1<0对于一切实数x 恒成立. ∵x 2-8x +20=(x -4)2+4>0,则由x 2-8x +20(m 2-1)x 2+2(m +1)x -1<0恒成立, 可得(m 2-1)x 2+2(m +1)x -1<0①恒成立.(1)当m 2-1=0,即m =±1时,若m =1,则不等式①为4x -1<0,不恒成立;若m =-1,则不等式①为-1<0,恒成立.∴m =-1可使不等式①恒成立.(2)当m 2-1≠0,则m ≠±1时,要使不等式①恒成立,则其对应二次函数y =(m 2-1)x 2+2(m +1)x -1图象开口应向下,且与x 轴没有交点.∴只需要满足⎩⎪⎨⎪⎧ m 2-1<0,[2(m +1)]2-4(m 2-1)(-1)<0. 解得-1<m <0.综合(1)(2)可得存在这样的m ,使不等式x 2-8x +20(m 2-1)x 2+2(m +1)x -1<0对于一切实数x 恒成立,且m 的取值范围为-1≤m <0.。
人教版选修八Unit 2 Cloning Grammar课时作业 (2)
Unit 2 Cloning Grammar课时作业第一节完形填空阅读下面短文,从短文后各题所给的A、B、C和D四个选项中,选出可以填入空白处的最佳选项。
I was a self-employed writer. But I had been in a bad 1 since my new neighbor moved in. Whenever I became 2 to write, I could hear a girl singing next door. She didn’t sing well at all, even3 -it was absolutely a headache for me.4 , it became a daily routine for me to5 . How couldI keep up my 6 and go on writing?One day, it was too noisy and my thoughts were entirely 7 . I had my husband go to 8 her about the matter. Minutes later, he returned. “That girl is only 17,” he9 with a sad look, “but she has bone cancer.” My mind suddenly went10 . “Her mother said tha t the more 11 it is, the louder her daughter sings. It helps her 12 the pain. The poor mother begs our pardon for interrupting us.” In a flash, I felt guilty about my thoughtless13 .From that day on, I no longer felt anything 14 , and even got used to her singing-I felt as if15 by the smell of flowers. Afterwards I was on business and happened to know the girl had been16 into a hospital. When I returned home in late summer, I 17 felt that something was 18 . I couldn’t hear the girl next door sing anymore.“However hard the winds blow, you will stray(走失) no more from my 19 …You shall believe that I am brave only with you…” Her singing always20 in my mind. I hope the voice is everlasting for you, me, and everyone.1. A. appetite B. condition C. mood D. state2. A. bored B. inspired C. safe D. afraid3. A. out of place B. out of fashion C. out of order D. out of tune4. A. Gradually B. Suddenly C. Surprisingly D. Particularly5. A. understand B. explain C. tolerate D. follow6. A. interests B. head C. hope D. spirits7. A. disturbed B. lifted C. buried D. touched8. A. indicate B. approach C. complain D. scold9. A. cried B. yelled C. sighed D. declared10. A. cold B. silent C. calm D. blank11. A. hurtful B. wonderful C. effortless D. difficult12. A. accelerate B. gather C. ease D. cover13. A. manners B. step C. movement D. action14. A. personal B. wrong C. complicated D. stubborn15. A. blown B. absorbed C. greeted D. moved16. A. admitted B. laid C. transformed D. suspended17. A. instead B. somehow C. otherwise D. anymore18. A. explicit B. abstract C. complex D. missing19. A. company B. distinction C. prejudice D. reputation20. A. develops B. rises C. flows D. changes第二节语法填空阅读下面材料,在空白处填入1个适当的单词或括号内单词的正确形式。
2018-2019学年高一物理人教版必修2课时作业:(二) 平抛运动含答案解析
取竖直向下为正方向)()要依据平抛运动在竖直方向上的分速度v y的大小及方向随时间的变化规律,结合图象的特点进行分析,作出推断.平抛运动的竖直分运动是自由落体运动,竖直竖直方向上的分速度v y随时间变化的图线应是过原点的一条倾斜直线,MN的左侧某点则所有抛出的小球在碰到墙壁前瞬间向延长线必交于水平位移OA 的中点,选项A 正确.答案:A5.以v 0的速度水平抛出一物体,当其水平分位移与竖直分位移相等时,下列说法错误的是( )A .速度的大小是5v 0B .运动时间是2v 0gC .竖直分速度大小等于水平分速度大小D .运动的位移是22v 20g解析:当其水平分位移与竖直分位移相等时,v 0t =12gt 2,可得运动时间t =2v 0g ,水平分速度v x =v 0,竖直分速度v y =gt =2v 0,合速度v =v 2x +v 2y =5v 0,合位移s =x 2+y 2=22v 2g ,对比各选项可知说法错误的是选项C.答案:C二、多项选择题6.关于平抛运动,下面的几种说法不.正确的是( ) A .平抛运动是一种不受任何外力作用的运动B .平抛运动是曲线运动,它的速度方向不断改变,不可能是匀变速运动C .平抛运动可以分解为水平方向的匀速直线运动和竖直方向的自由落体运动D .所有只受重力作用的物体都做平抛运动解析:平抛运动的物体只受重力,加速度为重力加速度,所以为匀变速曲线运动,A 错误、B 错误;由于水平方向速度不变,所以选项C 正确.答案:ABD7.关于平抛运动,下列说法正确的是( )A .由t =xv 0可知,做平抛运动的物体的初速度越大,飞行的时间越短B .由t =2hg 可知,做平抛运动的物体下落的高度越大,飞行的时间越长C .任意连续相等的时间内,做平抛运动的物体下落的高度之比为135……D .任意连续相等的时间内,做平抛运动的物体运动速度的改变量相等解析:由t =xv 0来计算时间,因x 不确定,故不能说v 0越大则t 越小,选项A 错误;物体做平抛运动的时间t =2hg ,因g 一定,故t ∝h ,选项B 正确;C 选项中没有说明从什么时间开始计时,故下落高度之比未必是135……,选项C 错误;因平抛运动的加速度恒定,故选项D 正确.答案:BD8.某人向放在水平地面的正前方小桶中水平抛球,结果球划着一条弧线飞到小桶的右侧(如图所示).不计空气阻力,为了能把小球抛进小桶中,则下次再水平抛球时,他可能做出的调整为( )A .减小初速度,抛出点高度不变在距地面高度一定的空中,一架战斗机由东向西沿水平方向匀速飞开始瞄准并投掷炸弹,炸弹恰好击中目标的斜面上的某点先后将同一小球以不同初速度水平抛出v1时,小球到达斜面时的速度方向与斜面的夹角小球到达斜面时的速度方向与斜面的夹角为=tanφ,φ=θ+α,无论=α2,故A、B错误,一质点做平抛运动先后经过A、B两点点时速度方向与水平方向的夹角为位置的竖直分速度大小之比.与水平方向的夹角为θ,求tan(1)13一小球从平台上水平抛出,恰好落在平台前一倾角为已知平台到斜面顶端的高度为h=斜面顶端与平台边缘的水平距离x.(sin53°=0.8,。
相似三角形课时2作业
初二数学练习⑸一、填空题1、如图①:AD ⊥BC ,∠BAC=90°,那么△ABC ∽ ∽ ,AD 2= ,AB 2=2、如图②:△ABC 与△DBC 相交于点O ,∠A=∠D ,图中相似三角形有 对,它们是3、如图③,BE 、CD 相交于点O ,CB 、ED 的延长线相交于点A ,且∠C=∠E ,图中相似三角形有 对,它们是4、等腰△ABC 的顶角是36°,若△ABC ∽△A ′B ′C ′,那么△A ′B ′C ′的底角是5、在△ABC 和△A ′B ′C ′中,∠A=∠A ′=85°,∠B=50°,∠C ′=45°,这两个三角形是 ,根据是6、如图④,AC ⊥BC ,∠ADC=90°,∠1=∠B ,若AC=5,AB=6,则AD= 二、选择题7、如图⑤,∠ABD=∠C ,AB=5,AD=3.5,则AC= ( )A 750B 507C 203D 320 8、如图⑥,CA ∥FG ∥BD ,若两个三角形相似构成一组相似三角形, 那么图中相似三角形的组数是 ( )A 1B 2C 3D 4 9、下列图形不一定相似的是 ( ) A 两个等边三角形 B 各有一个角是110°的两个等腰三角形 C 两个等腰直角三角形 D 各有一个角是45°的两个等腰三角形 10、如图⑦,AD 、BE 是△ABC 的高相交于点F ,图中共有相似三角形 ( )A 6对B 5对C 4对D 3对11、下列结论中不正确的是 ( ) A 有一个锐角相等的两个直角三角形相似 B 有一个锐角相等的两个等腰三角形相似C 有一个角为120°的两个等腰三角形相似 C 有一个角为60°的两个等腰三角形相似三、解答题 12、如图:已知△ABC 与△ADE 的边BC 、AD 相交于点O ,且∠1=∠2=∠3。
说明:(1)△ABC ∽△CDO ;(2)△ABC ∽△ADE13、如图:已知在Rt △ABC 中,∠ACB=90°,CD ⊥AB ,FE ⊥AB ,垂足为D 、E 。
2021-2022学年高中英语外研版必修4课时作业 2 Word版含答案
课时作业2Ⅰ.用所给动词的适当形式填空1.I ________ (sleep) at 12:00 p.m.2.By this time tomorrow, I ________ (lie) on the beach.3.This time next day they ________ (sit) in the cinema.4.We ________ (spend) the winter in Australia.5.The students ________ (watch) TV at seven this evening.6.I hope he ________ (find) a good job one day.7.That bus ________ (leave) in 10 minutes.8.I think the kids ________ (do) their homework when we get home.9.When he comes to my house tomorrow, I ________ (write) the report.10.This Saturday I will be very busy. I ________ (repair) my bike then.答案:1.will be sleeping 2.will be lying 3.will be sitting 4.will be spending 5.will be watching 6.will find7.is leaving8.will be doing9.will be writing10.will be repairingⅡ.单句语法填空1.—Will you be free at 11:30 ?—Sorry. I ________ (have) a meeting then.2.—Shall we meet tomorrow afternoon?—Not before 3 o'clock. I ________ (work) in the office then.3.Tomorrow we're going to play tennis in the afternoon. So at 15:00,we________(play) tennis.4.Do you think we ________ (still do) the same job in ten years' time?5.—________(you,see) Laura tomorrow?—Yes. Why?—I borrowed this book from her. Can you give it back to her?6.Now watch carefully and see what ________(happen) in the experiment.7.—It is said that another airport is being designed now.—Yes. It ________ (take) the experts another three days to finish the design.8.Tom, you uncle ________ (come) this afternoon.9.You ________(be) late if you ________ (not hurry).10.Use your head and you ________ (find) a better way.11.I ________ (enjoy) a concert at 8:00 pm tomorrow.12.I ________ (have) lunch at 12 o'clock when CCTV ________ (start) to broadcast news.13.—I will give an appointment on Friday, the 22nd.Will that be all right?—I am sorry. I ________ (work) on 22nd.14.—Where is my phone?—I ________ (get) it for you.15.What do you think the boys ________ (do) when we get home?答案:1.will be having 2.will be working 3.will be playing 4.will be still doing 5.Will you be seeing/Will you see 6.will happen7.will take8.iscoming/will come9.will be; don't hurry10.will find11.will be enjoying12.will be having; starts13.will be working14.will get15.will be doingⅢ.完形填空Mrs. Green was over seventies, but she still drove her old car like a woman half her age. She loved driving very fast, and was proud of the __1__ that she had never, in her thirty-five years of driving, been punished __2__ a driving offence(犯规,犯法).Then one day she nearly __3__ her record. A police car __4__ her, and the policeman in it saw her __5__ a red light without stopping. Of course, she was stopped. It seemed __6__ that she would be punished. When Mrs. Green came up to the __7__,he looked at her seriously and said that she was __8__ old to drive a car, and that the__9__ why she had not stopped at the red __10__ was most probably that her eyes had become weak __11__ old age, so that she had simply not seen it.When the judge had finished what he was __12__,Mrs. Green opened the big handbag she was __13__ and took out her sewing. Without saying a word, she __14__ a needle with a very small eye, and threaded it at her first attempt.When she had __15__ done this, she took the thread out of the needle again and handed __16__ the needle and the thread to the judge, saying,“Now it is your __17__.I suppose you drive a car, and that you are quite sure about your own eyesight.”The judge took the __18__ and tried to thread it. After half a dozen tries, he had still not succeeded. The case against Mrs. Green was __19__,and her record __20__ unbroken.1.A. fact B. actionC. skillD. age2.A. about B. onC. toD. for3.A. kept B. wonC. missedD. lost4.A. watched B. chasedC. followedD. stopped5.A. pass B. goC. runD. rush6.A. sure B. ableC. certainD. like7.A. police B. judgeC. officerD. captain8.A. so B. veryC. tooD. quite9.A. cause B. reasonC. matterD. trouble10.A. light B. lampC. signD. one11.A. with B. becauseC. forD. of12.A. speaking B. sayingC. talkingD. telling13.A. holding B. gettingC. carryingD. bringing14.A. took B. broughtC. pickedD. chose15.A. almost B. hardlyC. successfullyD. successful16.A. both B. allC. neitherD. either17.A. time B. turnC. chanceD. job18.A. thread B. glassesC. needlesD. needle19.A. dismissed B. passedC. settledD. studied20.A. was B. keptC. seemedD. remained答案与解析:1.A词语辨析题。
2019-2020学年英语人教版必修2作业与测评Unit 5 Section Ⅱ The Language Points of Reading 课时作业(二
课时作业(二)对应学生用书P53[基础题]Ⅰ单词拼写1.I walked past, ________ (假装) not to see her.答案:pretending2.Police asked ________ (过路人) if they had seen the accident happen.答案:passers-by3.During holidays, the city put on ________ (额外的) buses to carry passengers.答案:extra4.He likes to tell ________ (幽默的) stories to children when he is free.答案:humorous5.I ________ (附加) a photo to my application form just now.答案:attached6.He can e________ no more money than you can.答案:earn7.His father is an a________ of Beijing Opera.答案:actor8.He has f________ the habit of having a walk after supper.答案:formed9.I have no c________ on me. Can I pay you later?答案:cash10.Hangzhou is considered to be one of the most a________ places in China.答案:attractiveⅡ选词填空dream of; to be honest; attach ... to ...; in cash; play jokes on; rely on; be familiar with; or so; break up; be based on1.A good marriage ________ trust.答案:is based on2.It's impolite to ________ the disabled.答案:play jokes on3.IOC stands for International Olympic Committee. But ______, I didn't know it before.答案:to be honest4.The girl once ________ becoming a teacher like her mother.答案:dreamed of5.The Chinese ________ great importance ________ having a family reunion dinner on New Year's Eve.答案:attach; to6.We don't know the reason why they have ________ with each other.答案:broken up7.The people on the island ________ a spring for their water.答案:rely on8.—________ you ________ the song?—Yes. There was a time when the song was quite popular.答案:Are; familiar with9.When you call on a Frenchman, you may talk with him for an hour ________,and at that time neither coffee nor water is offered.答案:or so10.—Can I pay the bill by check?—Sorry, sir. But it is the management rule of our hotel that payment shall be made ________.答案:in cashⅢ单句语法填空1.In the following few days,the men and women ________ (help) Rockaway recover inspired Natalie.答案:helping2.Scientists have advanced many theories about why human beings cry tears, noneof ________ has been proved.答案:which3.He likes playing jokes________his friends, so he is not popular_______them.答案:on; with4.His name is familiar________us but we are not familiar________his character.答案:to; with5.His son pretended ________ (read) when he came in.答案:to be reading6.His car broke________on the way,and that was why he was late for the meeting.答案:down7.The Chinese people have been dreaming of ________ (go) into space for a long time. Today, it's become true.答案:going8.How much importance do you attach ________ the latest events?答案:to9.John invited about 40 people to his wedding,most of ________ are family members.答案:whom10.The toys are ________ (attract) to children due to the appearance.答案:attractiveⅣ单句改错1.When the boss came, she pretended to working hard.__________________________________________________________________ 答案:working前加be2.They sell drinks to passer-bys.__________________________________________________________________ 答案:passer-bys→passers-by3.This kind of situation was all too familiar with John.__________________________________________________________________ 答案:with→to4.She earns a living with singing in a nightclub.__________________________________________________________________ 答案:with→by5.He dreams of become a famous violinist one day.__________________________________________________________________ 答案:become→becoming[能力题]阅读理解AResearch done at the University of California-Ir-vine shows that young children taking music lessons have a greater ability to learn math and science. Coordination and concentration are also improved. Mastering a song or technique allows children to feel a sense of achievement and a desire to move on to the next challenge. These feelings of pride can also improve W1their confidence in the classroom.The lazy days of summer are a great time to introduce and expose your child to P1all sorts of music.1.Introduce babies to music by singing lullabies (摇篮曲) to them.2.Help younger children relate to music by asking about the sounds they hear. Does that drum sound happy or sad? Would an elephant sound like that high flute (长笛), or that deep bassoon (低音管)?3.Look into a wide variety of musical toys and records of songs that are available for children.4.Take your family to performances at local schools or universities.5.If you and your child decide on P2music lessons, look for a teacher who can get along well with children.6.Talk to other parents whose children take lessons for suggestions,or consult with P3the music teacher at your child's school. Keep your child's personality W2in mind,too. An active child might enjoy singing with a choir or playing with a band more than music lessons.7.If you want to learn to play the piano yourself,you'd better take some lessons. Show your child that it takes time and practice to master a new skill. Just make sure not to turn this into a competition.8.Encourage your child by asking her/him to play for you.9.Never use music practice as punishment!1.What's the main idea of the first paragraph?A.How children learn math and science.B.Music lessons will do good to children.C.Mastering a song is important for children.D.How to improve children's confidence.答案:B段落大意题。
课时作业2:Unit5 第二课时
Do you want to watch a game show?SevtionA(3a-3c)课时作业一.根据首字母提示写单词。
1. Tonight I’m going to watch an a_________ movie.2. Some boys e________ to talk with the actor in the meeting.3. I don’t m_____________the talk show” Healthy Living”4. “Animal World “ is the moist p___________ in China.5.What do you t_________ of the talk show?6. The basket is empty. There ‘s n________ in it.7. Wash your dirty hands with the s___________.8.Thanks for j__________ our party.9.My mom enjoys w__________ sitcoms.10.I can’t stand soap o___________.二.选择填空( )1.I turned _____ the radio and listened ________ the music.A. on , onB. to, toC. on, toD. in, in ( )2.My father enjoys __________ newspapers.A. readB. readsC. to readD. reading ( )3.The sitcom is very interesting, I ___________ it.A. likeB. don’t likeC. don’t mindD. can’t stand( )4.I __________ soap operas. They are boring.A. can’t standB. likeC. loveD. don’t mind( )5.-I think football is very interesting.-I agree __________you.A. toB. withC. onD. at:( )6.We didn’t go to movies______the bad weather.A.becauseB. whenC.because ofD. so ( )7.________ your father __________ game shows?A. What do, think ofB. What are, thinkC. What does, think ofD. What is , think( )8.-Are you free this evening?-No, I have a lot of homework ___________.A. to doB. doingC. doesD. do ( )9.-Can’t you hear ______? -No, I can hear__________.:A. anything, nothingB. anything, anythingC. something, nothingD. something, something[ ( )10.Li Lida a ___________ boy crossed the Qiongzhou Channel in June 2000.A. thirteen-year-oldB. thirteen-years-oldC. thirteen years oldD. thirteen- years old三.综合填空阅读短文, 根据短文内容和已给出的首字母, 在空白处填入适当的单词。
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第2章组成细胞的分子课时作业2细胞中的元素和化合物细胞中的无机物时间:25分钟满分:100分一、选择题(每小题5分,共60分)1.组成生物体的化学元素在生物体中起重要作用,下列对几种元素与光合作用关系的叙述中,正确的是()A.C是组成碳水化合物的基本元素,在光合作用中C元素从CO2经C3、C5形成(CH2O) B.N是叶绿素的组成成分,缺少N会影响植物进行光合作用C.O是构成有机物的基本元素之一,光合作用制造的有机物中的氧来自H2OD.P是构成ATP的必需元素,光合作用中光反应和暗反应过程中有ATP的合成解析:C是组成碳水化合物的基本元素,在光合作用中C元素从CO2经C3形成(CH2O),不经过C5。
光合作用制造的有机物中的氧来自CO2而不是来自H2O。
P是构成ATP的必需元素,光合作用中只有光反应过程中有A TP的合成,暗反应过程中没有ATP的合成。
N是叶绿素的组成成分,缺少N会影响植物进行光合作用。
答案:B2.(2011·江西南昌调研)下列有关细胞中元素和化合物的叙述,正确的是()A.C是构成细胞的基本元素,在人体活细胞中含量最多B.脂肪分子中含H比糖类多,是主要的能源物质C.氨基酸脱水缩合产生水,水中的氧来自氨基酸的羧基D.RNA和DNA主要组成元素的种类不同,碱基种类不完全相同解析:在人体活细胞中氧含量最多。
脂肪分子中含H比糖类多,含O比糖类少,是主要的储能物质,主要的能源物质是糖类。
RNA和DNA主要组成元素的种类相同,碱基种类不完全相同。
答案:C3.(2011·山东济南二模)元素和化合物是细胞的物质基础,下列相关叙述正确的是() A.ATP、染色体中含有的五碳糖都是核糖B.mRNA是翻译的模板,DNA是复制和转录的模板C.具有生物催化作用的酶都是由氨基酸组成的D.性激素、生长激素、胰岛素与双缩脲试剂反应呈紫色解析:染色体主要由DNA和蛋白质组成,所以染色体中含有的五碳糖主要是脱氧核糖;有的酶化学本质是RNA,由核糖核苷酸组成;性激素为固醇类小分子,并非蛋白质,不与双缩脲试剂反应。
答案:B4.(2010·江西南昌一模)下列关于元素及化合物的叙述,正确的是()A.N不仅是生物膜系统的重要组成元素,也是脂肪、A TP、DNA等不可缺少的组成元素B.人体内环境中的Na+有维持血浆渗透压的功能C.无论是鲜重还是干重,碳元素占人体细胞的百分比最高D.碳元素在生物群落与无机环境之间主要以二氧化碳和含碳有机物的形式循环解析:脂肪中不含N元素。
氧元素占人体细胞鲜重的百分比最高。
碳元素在生物群落与无机环境之间主要以二氧化碳的形式循环。
答案:B5.下列关于细胞中化合物的叙述,错误的是()A.细胞中的化合物是细胞的结构和生命活动的基础B.化合物中的蛋白质、脂质和核酸是构成细胞内生命物质的主要成分C.构成细胞的任何一种化合物都不能单独完成某一项生命活动D.构成细胞的任何一种化合物都能在无机自然界找到解析:构成细胞的化合物具有生命的特殊性,在无机自然界中不一定都能找到。
答案:D6.(2010·重庆一检)下图是由4个圆所构成的元素概念的关系图,其中4为最大圆,3、2、1依次减小。
试判断符合这种关系的是()A.1.大量元素、2.主要元素、3.基本元素、4.最基本元素B.1.基本元素、2.最基本元素、3.大量元素、4.主要元素C.1.最基本元素、2.基本元素、3.主要元素、4.大量元素D.1.主要元素、2.大量元素、3.最基本元素、4.基本元素解析:最基本元素为C,基本元素是C、H、O、N,主要元素是C、H、O、N、P,大量元素为C、H、O、N、P、K、S、Ca、Mg。
因此,C选项符合要求。
答案:C7.如图所示细胞中各种化合物占细胞鲜重的含量,以下按①②③④顺序排列正确的是()A.水、蛋白质、糖类、脂质B.蛋白质、糖类、脂质、水C.水、蛋白质、脂质、糖类D. 蛋白质、水、脂质、糖类解析:细胞中的化合物含量由高到低的顺序依次是水、蛋白质、脂质和糖类。
答案:D8.人的红细胞必须生活在含有0.9%的氯化钠的溶液中,医生常给脱水病人注射0.9%的生理盐水。
因为红细胞在蒸馏水中会因吸水过多而涨破;在浓盐水中会因失水过多而皱缩,因而失去输送氧气的功能。
这说明()A.水分子容易进出细胞B.无机盐离子容易进出细胞C.红细胞的特性造成的D.无机盐对维持细胞的形态和生理功能有重要功能解析:红细胞的生活环境为浓度相当于0.9%的氯化钠的溶液,当外界环境溶液的浓度发生变化时,细胞的形态和功能都将随之发生变化。
这说明红细胞的形态和生理功能都与氯化钠有关,即与无机盐有关。
答案:D9.下列关于酒精在生物实验中的相关应用,叙述不正确的是()A.在使用苏丹Ⅲ鉴定脂肪的实验中,酒精的作用是洗去实验材料上的浮色B.采集的土壤小动物可以放在体积分数为70%的酒精溶液中保存C.制作洋葱根尖细胞有丝分裂装片时,使用的解离液成分是盐酸和酒精D.在观察细胞内DNA和RNA分布的实验中,用酒精来改变细胞膜通透性,加速染色剂进入细胞解析:在观察细胞内DNA和RNA分布的实验中,盐酸能改变细胞膜的通透性,加速染色剂进入细胞。
答案:D10.(2011·吉林期末)关于生物体内水和无机盐的叙述,不正确的是()A.体内参与运输营养物质和代谢废物的水是自由水B.某些无机盐是组成ATP、RNA和纤维素的必需成分C.生物体内无机盐浓度的大小会影响细胞的吸水或失水D.自由水与结合水的比例随生物个体代谢的强弱而变化解析:纤维素只由C、H、O三种元素组成,没有无机盐。
答案:B11.(2011·广东汕头质检)下列关于人体内蛋白质的叙述中,正确的是()A.蛋白质具有多样性,是由于氨基酸的种类、数目、排列顺序和空间结构不同B.指导蛋白质合成的基因中的碱基有C、G、A、T、UC.人体内的酶都是蛋白质,激素不一定是蛋白质D.蛋白酶也是蛋白质,能够把蛋白质分解为氨基酸解析:这是一道综合性的试题,考查蛋白质的组成元素、合成和功能。
蛋白质具有多样性,是由于氨基酸的种类、数目、排列顺序和肽链的空间结构不同。
指导蛋白质合成的基因中含有碱基C、G、A、T。
人体内的酶都是蛋白质,但激素不一定是蛋白质,如性激素是固醇。
蛋白酶是蛋白质,一般只能把蛋白质分解为多肽。
答案:C12.人体血液中含钙量约为0.01 g/100 mL,当血钙过低时,可导致肌肉痉挛,甚至抽搐,这说明无机盐的作用之一是()A.构成肌细胞的重要成分B.维持pH稳定C.能刺激肌细胞产生抽搐D.维持细胞的正常生理功能解析:不同的无机盐其生理作用不同,如HCO3-、H2PO4-等能维持血浆pH的稳定;Ca2+维持细胞正常的生理功能,当血液中含钙量偏低时,肌肉细胞正常的生理功能受障碍,会导致肌肉痉挛、抽搐等现象。
答案:D二、简答题(共40分)13.(12分)分析下列图表回答问题:细胞中主要化合物相对含量(1)(2)组成生物体的最基本元素占细胞鲜重的________。
(3)构成人体的化学元素中C、O、H含量最多的原因是:____________。
氮含量较多的原因是____________。
(4)硫元素主要存在于有机化合物的种类是_____________________________。
(5)氧元素在细胞总量中占比例最大,为什么不是最基本的元素?________________________________________________________________________。
答案:(1)C、H、O、N、P、S(2)18%(3)含量最多的化合物水中含H、O,有机物中都含C、H、O人体中含有较多的蛋白质(4)蛋白质(5)细胞中的两大生命物质——蛋白质和核酸是由碳原子连接成链状或环状构成的,不是由氧原子为骨架的,所以碳是最基本元素14.(10分)在目前已发现的一百多种元素中,许多元素存在同位素,且其同位素大多具有放射性。
放射性同位素示踪技术在生产、生活和科研中有着十分广泛的用途。
试回答下列问题:(1)请你为下面的实验选择恰当的放射性同位素:①18O②14C③15N④32P⑤35S⑥3H科学家在探究噬菌体的遗传物质的过程中,用________标记一部分噬菌体的蛋白质,用________标记另一部分噬菌体的DNA,最终探明了噬菌体的遗传物质是它的DNA。
(2)上图是为研究光合作用而设计的装置的一部分,甲、乙试管中分别培养有单细胞绿藻。
为甲提供带标记18O的C18O2和普通的H2O,为乙提供普通CO2和带18O标记的H218O。
在适宜的光照条件下,很快测得甲释放O2,而乙释放18O2。
经过一段较长的时间后,发现甲装置也释放出18O2,其原因是:___________________________________________ ________________________________________________________________________。
(3)把菜豆幼苗放在含32P的培养液中培养,一小时后测定表明,幼苗各部分都含32P。
然后将该幼苗移到不含P的培养液中,数天后32P将________________________________ ________________________________________________________________________。
解析:蛋白质的特征元素为S,核酸的特征元素为P,所以用其相应的放射性同位素35S、32P分别标记蛋白质、核酸,可以准确的追踪这两种化合物,不会造成混淆。
在光合作用过程中CO2中的O可在CO2还原阶段被转移到H2O中,所产生的水又可参与光反应产生O2。
32P被幼苗吸收后逐渐用于合成自身的化合物以构建机体,所以数天后将在植物体内各细胞中出现。
答案:(1)⑤④(2)光合作用过程中产生了H218O(其中的氧来自C18O2),这些水又可以作为光合作用的原料被分解(3)在植物体内各细胞中出现15.(18分)被子植物花粉管的萌发及其结果,一般与温度、促进物、氧气等条件有关,请任意选择其中一项作为研究课题,并在提供的实验器材中选取合理器材进行实验,完成下面的实验报告。
(1)实验目的:__________________________________________________________。
(2)实验原理:__________________________________________________________。
(3)实验器材:新鲜葱兰花、恒温箱、葡萄糖溶液、琼脂、硼酸溶液、稀盐酸、蒸馏水、滴管、镊子、载玻片、显微镜等。
(4)实验步骤:___________________________________________________________________________________________________________________________________ ________________________________________________________________________。