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．。
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，。
新课标A版高中数学选修2-3课时作业：2 Word版含答案
课时作业(二)1．将5名大学毕业生全部分配给3所不同的学校，不同的分配方式的种数有( ) A．8种B．15种C．125种 D．243种答案 D解析每名大学生有三种不同的分配方式，所以共有35种不同的分配方式．2．从集合A＝{0,1,2,3,4}中任取三个数作为二次函数y＝ax2＋bx＋c的系数a，b，c.则可构成不同的二次函数的个数是( )A．48 B．59C．60 D．100答案 A解析由于是二次函数，需分三步确定系数a，b，c，a有除0之外的四种选法，b有四种选法，c有三种选法，故有4×4×3＝48种．3．从黄瓜、白菜、油菜、扁豆4种蔬菜品种中选出3种，分别种在不同土质的三块土地上，其中黄瓜必须种植，不同的种植方法共有( )A．24种 B．18种C．12种 D．6种答案 B解析(直接法)：黄瓜种在第一块土地上有3×2×1＝6种．同样，黄瓜可种在第二块、第三块土地上，共有不同的种法有6×3＝18种．(间接法)：4种选3种，种在三块地上有4×3×2＝24种，其中不种黄瓜有3×2×1＝6种，共有不同种法24－6＝18种．4．已知异面直线a，b上分别有5个点和8个点，则经过这13个点可以确定不同的平面个数为( )A．40 B．13C．10 D．16答案 B解析根据一条直线与直线外一点可确定一个平面，因此可分为两类；第一类，直线a与直线b上的点所确定的平面有8个平面；第二类，直线b与直线a上的点所确定的平面有5个，根据分类加法计数原理，共有8＋5＝13个不同平面．5．书架上原来并排放着5本不同的书，现要再插入3本不同的书，那么不同的插法共有( )A．336种 B．120种C．24种 D．18种答案 A解析我们可以一本一本的插入，先插一本，可在原来5本书形成的6个空当中插入，共有6种插入的方法；然后再插第二本，这时书架上有6本书形成7个空当，有7种插入方法；再插最后一本，有8种插法，所以共有6×7×8＝336种不同的插法．6．有5个不同的棱柱、3个不同的棱锥、4个不同的圆台、2个不同的球，若从中取出2个几何体，使多面体和旋转体各一个，则不同的取法种数是( )A．14 B．23C．48 D．120答案 C解析分两步：第一步，取多面体，有5＋3＝8种不同的取法，第二步，取旋转体，有4＋2＝6种不同的取法．所以不同的取法种数是8×6＝48种．7．如图所示，用不同的五种颜色分别为A，B，C，D，E五部分着色，相邻部分不能用同一种颜色，但同一种颜色可以反复使用，也可不使用，则符合这些要求的不同着色的方法共有( )A.500种 B．520种C．540种 D．560种答案 C解析按照分步计数原理，先为A着色共有5种，再为B着色共有4种(不能与A相同)，接着为C着色有3种(不与A，B相同)，同理依次为D，E着色各有3种，所以不同着色的方法共有N＝5×4×33＝540(种)．8．已知集合M＝{1，－2,3}，N＝{－4,5,6，－7}，从两个集合中各取一个元素作为点的坐标，则在直角坐标系第一、第二象限中的不同点的个数有( )A．18个 B．16个C．14个 D．10个答案 C解析此问题可分两类：①以集合M中的元素作为横坐标，集合N中的元素作为纵坐标，集合M中任取一个元素的方法有3种，要使点在第一、第二象限内，则集合N中只能取5,6两个元素中的一个，有2种方法，根据分步乘法计数原理有3×2＝6个；②以集合N中的元素作为横坐标，集合M中的元素为纵坐标，集合N中任取一个元素的方法有4种，要使点在第一、第二象限内，则集合M中只能取1,3两个元素中的一个，有2种方法，根据分步乘法计数原理，有4×2＝8个．综合以上两类，利用分类加法计数原理，共有6＋8＝14个．故选C.9．从数字1,2,3,4,5,6中取两个数相加，其和是偶数，共得________个偶数．答案 4解析分两类，3个奇数两两相加，3个偶数两两相加，都得偶数，又1＋5＝2＋4,3＋5＝2＋6，所以可得不同的偶数有3＋3－2＝4个．10．从正方体的6个表面中取3个面，使其中两个面没有公共点，则共有________种不同的取法．答案12解析分两步完成这件事，第一步取两个平行平面，有3种取法；第二步再取另外一个平面，有4种取法，由分步计数原理共有3×4＝12种取法．11．动物园的一个大笼子里，有4只老虎，3只羊，同一只羊不能被不同的老虎分食，问老虎将羊吃光的情况有多少种？解析因为3只羊都被吃掉，故应分为三步，逐一考虑．每只羊都可能被4只老虎中的一只吃掉，故有4种可能，按照分步乘法计数原理，故有4×4×4＝43＝64种．12．(2015·石家庄高二检测)某校高二年级一班有优秀团员8人，二班有优秀团员10人，三班有优秀团员6人，学校组织他们去旅游．(1)推选1人为总负责人，有多少种不同的选法？(2)每班选1人带队，有多少种不同的选法？(3)从他们中选出2个人管理生活，要求这2个人不同班，有多少种不同的选法？解析(1)分三类．第一类：从一班的8名优秀团员中产生，有8种不同选法；第二类：从二班的10名优秀团员中产生，有10种不同选法；第三类：从三班的6名优秀团员中产生，有6种不同选法．由分类加法计数原理得N＝8＋10＋6＝24种不同的选法．(2)分三步：第一步：从一班的8名优秀团员中选1人带队，有8种不同选法；第二步：从二班的10名优秀团员中选1人带队，有10种不同选法；第三步：从三班的6名优秀团员中选1人带队，有6种不同选法．由分步乘法计数原理得N＝8×10×6＝480种不同的选法．(3)分三类，每一类可分为两步．第一类：从一班、二班的优秀团员中各选1人，有8×10＝80种不同选法；第二类：从二班、三班的优秀团员中各选1人，有10×6＝60种不同选法；第三类：从一班、三班的优秀团员中各选1人，有8×6＝48种不同选法．由分类加法计数原理得N＝80＋60＋48＝188种不同的选法．13．用五种不同的颜色给图中的四个区域涂色，每个区域涂一种颜色．(1)共有多少种不同的涂色方法？(2)若要求相邻(有公共边)的区域不同色，则共有多少种不同的涂色方法？解析(1)由于1至4号区域各有5色方法有54＝625种．(2)第一类，1号区域与3号区域同色时，有5×4×4＝80种涂法，第二类，1号区域与3号区域异色时，有5×4×3×3＝180种涂法．依据分类加法计数原理知，不同的涂色方法有80＋180＝260(种)．14．用0,1，…，9这十个数字，可以组成多少个．(1)三位整数？(2)无重复数字的三位整数？(3)小于500的无重复数字的三位整数？(4)小于500，且末位数字是8或9的无重复数字的三位整数？(5)小于100的无重复数字的自然数？解析由于0不可在最高位，因此应对它进行单独考虑．(1)百位的数字有9种选择，十位和个位的数字都各有10种选择，由分步乘法计数原理知，符合题意的三位数共有9×10×10＝900(个)．(2)由于数字不可重复，可知百位数字有9种选择，十位数字也有9种选择，但个位数字仅有8种选择，由分步乘法计数原理知，符合题意的三位数共有9×9×8＝648(个)．(3)百位数字只有4种选择，十位数字可有9种选择，个位数字有8种选择，由分步乘法计数原理知，符合题意的三位数共有4×9×8＝288(个)．(4)百位数字只有4种选择，个位数字只有2种选择，十位数字可有8种选择，由分步乘法计数原理知，符合题意的三位数共有4×2×8＝64(个)．(5)小于100的自然数可以分为一位和两位自然数两类．一位自然数：10个．两位自然数：十位数字有9种选择，个位数字也有9种选择，由分步乘法计数原理知，符合题意的两位数共有9×9＝81(个)．由分类加法计数原理知，符合题意的自然数共有10＋81＝91(个)．►重点班选做题15．如图，某电子器件是由三个电阻组成的回路，其中共有6个焊接点A 、B 、C 、D 、E 、F ，如果某个焊接点脱落，整个电路就会不通，现在电路不通了，那么焊接点脱落可能性共有( )A ．6种B ．36种C ．63种D ．64种答案 C解析 每个焊点都有正常与脱落两种情况，共有26种情况，但其中有一种情况是各焊点都正常的情况，所以共有26－1种电路不通的情况．16．已知互不相同的集合A 、B 满足A ∪B ＝{a ，b }，则符合条件的A ，B 的组数共有________种．答案 9解析 当A ＝∅时，集合B ＝{a ，b }；当A 只有1个元素时，B 可以有2种情况，此时有2×2＝4种情况；当A ＝{a ，b }时，集合B ＝∅，{a }，{b }或{a ，b }，此时有4种情况，综上可知，符合条件的A 、B 共有1＋4＋4＝9种． 17．设椭圆x 2m ＋y 2n＝1的焦点在y 轴上，m ∈{1,2,3,4,5}，n ∈{1,2,3,4,5,6,7}，则这样的椭圆个数为________．答案 201．已知a ，b ∈{0,1,2，…，9}，若满足|a －b |≤1，则称a ，b “心有灵犀”．则a ，b “心有灵犀”的情形共有( )A ．9种B ．16种C ．20种D ．28种答案 D解析 当a 为0时，b 只能取0,1两个数；当a 为9时，b 只能取8,9两个数；当a 为其他数时，b 都可以取3个数．故共有28种情形．2．从个位数与十位数之和为奇数的两位数中任取一个，其个位数为0的概率是( )A.49 B.13C.29 D.19答案 D3．把10个苹果分成三堆，要求每堆至少有1个，最多5个，则不同的分法共有( ) A．4种 B．5种C．6种 D．7种答案 A4．从集合{1,2,3，…，10}中任意选出三个不同的数，使这三个数成等比数列，这样的等比数列的个数为( )A．3 B．4C．6 D．8答案 D5．若5名学生争夺3项比赛冠军(每一名学生参赛项目不限)，则冠军获得者有________种不同情况(没有并列冠军)?答案125思路本题关键在于搞清楚要以谁为主来研究问题．本题中完成的事件是5名学生争夺3项比赛冠军，这里，每名学生能获几项比赛冠军不确定，但这每一项比赛的冠军都可以由5个运动员中的1人获得，故应以“冠军”为主，即“冠军”作为位置，由5名运动员去占3个位置．解析每个冠军皆有可能被5名学生中任1人获得，3个冠军依次被获得的不同情况有53种．6．有1元、2元、5元、10元、50元、100元人民币各一张，则由这6张人民币可组成________种不同的币值．答案63解析对于每一张人民币来说，都有两种选择，用或不用，而都不用则形不成币值，由分步计数原理，可得N＝2×2×2×2×2×2－1＝26－1＝63(种)．7．三边长均为整数，且最大边长为11的三角形共有________个．答案36解析另两边长用x、y表示，且设1≤x≤y≤11，要构成三角形，必须x＋y≥12.当y取值11时，x＝1,2,3，…，11，可有11个三角形；当y取值10时，x＝2,3，…，10，可有9个三角形，……当y取值6时，x只能取6，只有一个三角形．∴所求三角形的个数为11＋9＋7＋5＋3＋1＝36.8．有A，B，C型高级电脑各一台，甲、乙、丙、丁4个操作人员的技术等级不同，甲、乙会操作三种型号的电脑，丙不会操作C型电脑，而丁只会操作A型电脑．从这4个操作人员中选3人分别去操作这三种型号的电脑，则不同的选派方法有________种(用数字作答)．答案8解析第1类，选甲、乙、丙3人，由于丙不会操作C型电脑，分2步安排这3人操作的电脑的型号有2×2＝4(种)方法；第2类，选甲、乙、丁3人，由于丁只会操作A型电脑，这时安排3人操作的电脑的型号有2种方法；第3类，选甲、丙、丁3人，这时安排3人操作的电脑的型号只有1种方法；第4类，选乙、丙、丁3人，同样也只有1种方法．根据分类加法计数原理，共有4＋2＋1＋1＝8(种)选派方法．9.如图所示，在连接正八边形的三个顶点而成的三角形中与正八边形有公共边的三角形有________个．答案40解析满足条件的有两类：第一类：与正八边形有两条公共边的三角形有m1＝8(个)；第二类：与正八边形有一条公共边的三角形有m2＝8×4＝32(个)，所以满足条件的三角形共有8＋32＝40(个)．10．在一块并排10垄的田地中，选择2垄分别种植A、B两种作物，每种作物种植一垄．为有利于作物生长，要求A、B两种作物的间隔不小于6垄，则不同的种植方法共有________种．答案12解析分两步：第一步，先选垄，如图，共有6种选法；第二步，种植A、B两种作物，有2种选法；因此，由分步乘法计数原理，不同的选垄种植方法有6×2＝12(种).。
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。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
(必修一·Unit 2)Ⅰ.单项填空1．I wouldn't marry Pat even if she ________ the last woman on earth.A．is B．wasC．had been D．were答案：D2．You can't do ________ your friends ask you to do.You'd better think first.A．everything B．anythingC．something D．nothing答案与解析：A考查不定代词辨析。
句意为：你不能做朋友让你做的每一件事件，你最好首先考虑一下。
not...everything表示部分否定。
3．It's so nice to hear from her again.________，we last met more than fifteen years ago.A．What's more B．That's to sayC．In other words D．Believe it or not答案：D4．It is requested that the reporter ________ to blame for the wrong report.A．referring to B．referring to asC．referred to be D．referred to being答案与解析：C当在复合句中出现表示“建议、主张或命令”的动词时，该从句应该使用虚拟语气，should常可省略；refer red to为过去分词短语作定语。
5．Whoever has ridden on a railway train knows how rapidly another train flashes by when it is traveling ________ the opposite direction.A．in B．underC．to D．with答案与解析：A direction常与in搭配，意为“朝……方向”。
6．You type almost anything，however unclear，into the space provided on Google and in a second it ________ with thousands of references.A catches up B．comes upC．ends up D．puts up答案与解析：B come up“出现”，相当于appear，与题意相符。
catch up“追上；赶上”；end up“结束”；put up“举起”。
7．When I began working ten years ago，I just earned too little to cover my living ________.A．bills B．pricesC．change D．expense答案与解析：D expense侧重指日常开支所需的“开支；费用”。
bill“账单”；price“价格”；change“零钱”。
8．Many students make great progress in listening ________ the large amount of time devoted to it.A．because of B．instead ofC．in case of D．in spite of答案与解析：A because of“因为，由于”，后接名词短语在句中作原因状语，此处表示“在听力方面取得巨大进步的原因”。
9．—Jim has his wife do all the housework！Isn't he wise?—Not really.He is ________.A．more wise than lazy B．wiser than lazyC．more lazy than wise D．laziest than wise答案与解析：C more...than...常用来对不同的人或事情的同一性质或方面的比较，后接两个对等成分，more后的形容词词尾不变，意为“与其说……不如说……”。
10．Some languages，________ Russian and German，are not easy to learn.A．for example B．such asC．namely D．that is答案与解析：B such as列举同类事物中的一部分，意为“例如”。
for example也用来举例说明，但其前后常用逗号隔开；namely相当于that is，意为“即”。
11．We can see monuments here and there.Those who have made great ________ to human beings and society will never be forgotten.A．advance B．progressC．contribution D．achievement答案与解析：C make contribution to为固定短语，意为“对……做出贡献”。
12．—Oh，it's you！I didn't ________ you.—I've just had my hair cut，and I'm wearing new glasses.A．recognize B．realizeC．know D．organize答案与解析：A由两人对话可知彼此是认识的，故用recognize，本题用一般过去式表示在说话之前没有认出来。
13．This habit is hard to form________，but in the long run，it will do you good.A．in future B．at presentC．in present D．in the future答案与解析：B句意：这种习惯目前很难养成，但是从长远来看，它对你有好处。
at present 目前，与下文的in the long run 相对应。
14．The professor can hardly find sufficient grounds ________ his argument in favor of the theory.A．which to base on B．on which to baseC．to base on which D．which to be based答案与解析：B考查“介词＋which＋to do”结构。
句意：教授几乎不能找到足够的理由支持他的理论。
base...on 意为“基于，作为……的基础”。
15．He commanded that all the gates ________ to search for the spy.A．should shut B．would be shutC．shut D．be shut答案与解析：D考查command后跟虚拟语气。
command后跟that从句，从句要用虚拟语气，即should＋动词原形，其中should可以省略。
Ⅱ.阅读理解An 11-month-old baby helped raise the alarm that her mother had fallen down unconscious by using a mobile phone.Amelia Boyle，known as Millie，picked up the ringing mobile and answered the call when her mother Elizabeth,20，fainted in the hall of their home.Linda Wright，Millie's grandmother，was on the other end of the line and heard the baby say “Who's that？”and “Mama”．The girl is not allowed to play with the mobile so Mrs.Wright knew something was wrong with Millie's mother，who has a history of fainting and fitting，and dialed 999.Miss Boyle，whose phone it was，woke up in her home in Braintree，Essex，to find police and ambulance crews at her door.She became confused and told them she had not called them.A few minutes later three paramedics arrived and examined her.She did not need hospital treatment.Miss Boyle said，“I went upstairs to get Millie some clothes.I came downstairs again and I was going to get her dressed up as normal.”“She was moving around playing with some toys when I suddenly fainted between the passage and the living room blocking the stairs.”“My mum phoned me back on the home phone and when she didn't get through，she tried on the mobile，then the home phone again.”She added，“I am so lucky to have Millie.”“Millie does not seem to be disturbed by it.She must have watched me open the phone—sheis not usually allowed to play with it because she tends to stick it in her mouth.”“She is a very clever little girl.I was proud of her anyway but now she is even more special.”Mrs.Wright said，“If Millie hadn't answered the phone，I wouldn't have known what had happened.”1．Miss Boyle fell down ill while her baby was________.A．answering Mrs.Wright's phone callB．following her mother up and downC．having fun with her toysD．playing with her mother's mobile phone答案与解析：C细节理解题。