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问题 选择题

已知一个等差数列共有2n+1项，其中奇数项之和为290，偶数项之和为261，则第n+1项为（　　）

A．30

B．29

C．28

D．27

答案

∵奇数项和S1=

(a1+a2n+1) (n+1)
2
=290

∴a1+a2n+1=

580
n+1

∵数列前2n+1项和S2=

(a1+a2n+1)(2n+1) 
2
=290+261=551

∴

S1
S2
=
(a1+a2n+1) (n+1)
2
(a1+a2n+1)(2n+1)
2
=
2n+1
n+1
=
290
551

∴n=28

∴n+1=29

故选B

填空题

函数y=x+2cosx在区间[0，π]上的最大值为______．
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完形填空

If you are studying English, the Language Study Fair (游乐会)that is being held this month will certainly attract you. The fair is going on between the 28th and 30th of June at the National Education Centre. It is held to answer all your questions about self-study no matter how your English is.

The Language Study Fair gives a very good chance for you to see and to get all kinds of information to help you improve the way you study. Over 350 producers of educational materials (材料)will be at the fair. Come along to this, and you won’t waste your money in the future on materials that are out-of-date, or books that you just don’t need.

We’ve got lots of different things for you to see and hear. There will be stands (展台)showing different kinds of self-study textbooks and talks by educational speakers on the best ways to study by yourself. We’re sure you’ll also enjoy watching people using the latest computer programs to make studying English alone so much easier. This is for you to make good decisions about what to buy. You can come to the fair from nine thirty to five. Tickets cost ￡5 each, or ￡3 if you’re a full-time student. All tickets can be booked by ringing the ticket hotline. The number is 9847711.

So, we hope to see you there!

小题1:Who will go to the Language Study Fair?

                                                                                  

小题2:What will attract those who go to the Language Study Fair ?

                                                                                  

小题3:What will you buy if you want to make studying English much easier?

                                                                                  

小题4:What is the opening time of the fair ?

                                                                                  

小题5:How can you get a ticket for the fair ?

                                                                                  
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