6.(2009重庆卷理)已知双曲线的左、右焦点分别为，若双曲线上存在一点使，则该双曲线的离心率的取值范围是　　　　　 ．

解法1，因为在中，由正弦定理得

则由已知，得，即，且知点P在双曲线的右支上，

设点由焦点半径公式，得则

解得由双曲线的几何性质知，整理得

解得，故椭圆的离心率

解法2 由解析1知由双曲线的定义知　　

，由椭圆的几何性质知所以以下同解析1.

5.(2009重庆卷文)已知椭圆的左、右焦点分别为，若椭圆上存在一点使，则该椭圆的离心率的取值范围为　　　　　 ．

[答案]

.　　 解法1，因为在中，由正弦定理得

则由已知，得，即

设点由焦点半径公式，得则

记得由椭圆的几何性质知，整理得

解得，故椭圆的离心率

解法2 由解析1知由椭圆的定义知　　

，由椭圆的几何性质知所以以下同解析1.

4.(2009全国卷Ⅰ文)若直线被两平行线所截得的线段的长为，则的倾斜角可以是

　　　　 ①　 ②　 ③　 ④　　 ⑤　　

其中正确答案的序号是　　　　　 .(写出所有正确答案的序号)

[解析]本小题考查直线的斜率、直线的倾斜角、两条平行线间的距离，考查数形结合的思想。

解：两平行线间的距离为，由图知直线与的夹角为，的倾斜角为，所以直线的倾斜角等于或。故填写①或⑤

3.(2009四川卷理)若⊙与⊙相交于A、B两点，且两圆在点A处的切线互相垂直，则线段AB的长度是　　　　　 w

[考点定位]本小题考查圆的标准方程、两直线的位置关系等知识，综合题。

解析：由题知，且，又，所以有，∴。

2.(2009湖北卷文)过原点O作圆x²+y^2_－6x－8y+20=0的两条切线，设切点分别为P、Q，则线段PQ的长为　　　　　　 。

[答案]4

[解析]可得圆方程是又由圆的切线性质及在三角形中运用正弦定理得

1. (2009天津卷理)若圆与圆(a>0)的公共弦的长为，

则___________　 　　。

[考点定位]本小题考查圆与圆的位置关系，基础题。

解析：由知的半径为，由图可知解之得

21.It's bad/good for 对...有害处 　eating more fruit is good for health. 　Don't read in bed. It's bad for your eyes. 　22.It's important/impossible/impolite/difficult for sb. to do sth.对于某人来说做...很重要的 　At school, it's very important for every student to keep their own classrooms clean and tidy. 　Although it is raining heavily, it looks that it's impossible for him not to finish the last 200 meters. 　23. It's time for .../to do sth. 对于...来说做...的时间了 　It's time for us to borrow books from the library. 　It's time for Tom to take medicine. 　24. It's two meters(years) long(old)它两米长(两岁大) 　He is two meters tall. 　The river is twenty meters wide. 　25. keep sb. doing sth 让某人一直做某事 　The headmaster kept me waiting for two hours last time. 　Why do you keep laughing all the time? 　26. keep/make sth. +adj. 让...一直保持... 　It's important for us to keep calm in danger. 　The movie was so sad that it made us cry. 　27. like to do /like doing 喜欢做.... 　My younger sister likes singing and dancing very much. 　What kind of books does she like reading in her free time? 　28. make/let sb.(not)do sth. 让某人做/不做某事 　Make him not lend the book to my younger brother, he will break it. 　To learn English well, the teacher always makes us read aloud in the morning. 　29. neither...nor 既不...也不 　We should come to the party just ath the right time, neither too early nor too late. 　It's neither too cold, nor too hot here all the year round. 　30. not... at all 根本不 　Although life is difficult, each of us doesn't want to give up our hope at all. 　Some have several girlfriends and others have none at all! 　31. not only... but also...　 不仅...而且 　Mike not only finished doing his homework but also helped his sister with her English. 　Today some newly-produced mobile phones can be used not only for taking photos but also for downloading songs from the Internet. 　32. not... until 直到...才 　He didin't stop to have a rest until he finished cleaning the old man's room. 　I didn't understand my mother's love to me until I talked with her yesterday. 　33. one ...the other/ some ...others　 一个…另一个；一些…另一些 　These are my two favotite books. One is called The Monky King, the other is called Harry Potter. 　Somepople say the Indian films are booring, but others say they are great. 　34. see/hear sb do(doing)sth 看见某人做了/正在做 　I heard my parents quarreling after supper. 　I heard someone singing in the next room. 　I heard somone knock a the door when I was cooking. 　35. so... that　 如此…以至于 　The noise outside was so big that we couldn't hear waht the teacher said. 　Kate was so angry that she couldn't say a word. 　36.spend...on(in doing)sth　 在…方面花费 　He spent so much time (in) playing computer games that he was not interested in his lessons. 　She spends $100 on clothes every week. 　37. stop/prevent sb. from doing sth. 阻止某人做某事 　Nothing can stop me from going swimming this afternoon. 　For years, Mike has kept studying how to stop middle school students from losing themselves in net games. 　38. stop to do /doing停下来去做某事 　The boss kept the workers working all the time until they finished all the work. 　Tell him not to stop to rest; it's important moment now. 　39. take /bring sth with sb. 随身携带 　Get the luch which you take with yourself ready, it's time for a meal. 　My friend brought many chocolates with him to visit me. 　40.There is something wrong with... 出了问题/毛病 　There si something wrong with my TV, so we can't watch the match. 　There's something wrong with my computer. Can you help me? 　41. too...to　 太…以至于不能… 　Hearing the news of successful launch of Shenzhou-7, many people were too excited to sleep the whole night. 　The box is too heavy for me to move. 　42. used to 过去常常 　She used to spend a lot of time playing computer games. 　Ther used to be a hospital. 　43. What about.../How about...?　 …怎么样呢？ 　How about going out for a walk after supper? 　I 'm too busy to go tho the movies with you today.How about tomorrow?

1.as soon as　 一……就 　He called me up as soon as he came back to Beijing. 　Please call me as soon as you finish your homework. 　2.not as/so ……as 和……一样；不如 　I think English is as important as maths 　For me, basketball is as interesting as football. 　3.as……as possible 尽可能的 　Kids in the West usually get ready for as many gifts as possible. 　We should speak English as much as we can in class. 　4.be afraid of doing sth./that 害怕做某事、害怕担心 　Children are always afraid of the dark. 　I used to be afraid of the dark. However, I am not now. 　5.be busy doing 忙于做某事 　Mom is always busy cooking when I get home. 　People in Beijing are busy getting ready for the Olympic Games. 　6.be famous /late/ready/sorry for… 以……著名 　He hurried to school yesterday, but he was late for class. 　Look!The students are getting ready for the sports meeting. 　7.both…and　 两者都 　Students like both palying basketball and playing soccer. 　It's a good way to make both teachers and students happy. 　8.buy/give/show/send/pass/bring/lend/tell sb. sth. 为某人买某物 　If I were you, I'd give the money to charity. 　Yesterday Mary's mother bought her a new bike. 　9.give/show/bring/lend/send/pass/tell sth to sb. 把…给某人 　Please give this book to him. 　When you get to your home, please send this letter to your pen pal. 　10.either…or 要么…要么 　We can't allow him to stay at home, or he will either watch TV or play games. 　We're going to the park this Saturday, either by bus or by bike. 　11.enjoy/hate/finish/mind/keep/go on doing 喜欢做某事 　I kept him reading the text so that he could recite it quickly. 　Would you please keep holding the picture for me? 　12.get+比较级 变得越来越…… 　The weather is getting warmer and warmer. 　How do you feel now? Unfortuately, it's getting worse. 　14.get on with 与…相处 　It's hard to get on with a bad-tempered person. 　15.get ready for/ get sth. ready 为……作准备 　Look! The students are getting ready for the sports meeting. 　The next station is Dongdan. Please get ready for your arrival. 　16.had better (not) do　 最好做、不做 　You'd better help your parents do some housework once a week. 　You'd better not spend more time on this kind of game. 　17.help sb(to)do/help sb. with 　The boy helped the old man to carry a bunch of wood up the hills. 　He asked me to help him to solve the problem. 　18.don't think that　 认为…不 　I don't think that they will give up the chance of being volunteers. 　I don't think that he is reading now. 　19.I would like to.../ would you like to...?我想做 　Would you like to lend me your bike? 　Iwould like to look up some new words in it. 　20.It takes sb sometime to do sth. 花费某人...时间做某事 　It will take the workers two years to build the bridge. 　It took her 3 months to do this experiment. 　How long will it take the workers to rebuild the new school?

28．(上海6)函数的最小值是_____________________ .

答案

27．(湖南3)将函数的图象向左平移的单位后，得到函数的图象，则等于(　　 )

A．　 　　　　　　B．　　　　 C. 　　　　　　D.

答案D　 　，，，因为，所以等于