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问题 选择题
已知等差数列{an}的首项为4，公差为4，其前n项和为Sn，则数列 {
1
Sn
}的前n项和为（　　）
A．
n
2(n+1)
B．
1
2n(n+1)
C．
2
n(n+1)
D．
2n
n+1
答案

∵Sn=4n+

n(n-1)
2
×4=2n2+2n，

∴

1
Sn
=
1
2n2+2n
=
1
2
(
1
n
-
1
n+1
)．

∴数列 {

1
Sn
}的前n项和=
1
2
[(1-
1
2
)+(
1
2
-
1
3
)+…+(
1
n
-
1
n+1
)]=
1
2
(1-
1
n+1
)=
n 
2(n+1)
．

故选A．

阅读理解

Every year there is the Spring Festival in China. Usually it is in January or February. It’s the most important festival in China. So before it comes, everyone has to prepare things. They buy beef, pork, chicken, fruit and many other things. And they often make a special kind of food called “dumplings”. It means “come together” in Chinese. On the day before the festival, parents buy new clothes for their children and children also buy presents for their parents. On the festival eve, all the family members come back to their home. This is a happy moment. They sing, dance and play cards. When they enjoy the meal, they give each other the best wishes for the coming year.

They all have a good time.

根据短文内容，选择正确答案。（5分）

小题1:Which is the most important festival in China?          .

A．Mid-autumn Festival

B．Spring Festival

C．Children’s Day

D．May Day小题2:The Chinese usually have their Spring Festival in         .

A．January or February

B．February or March

C．September or October

D．December or January小题3: What’s the special kind of food for the Spring Festival in China?  .

A．Pork

B．Fish

C．Dumplings

D．Noodles小题4: The food “dumplings” mean “          ”.

A．be delicious

B．be hungry

C．come together

D．come back小题5: When they are having dinner on the festival eve, the Chinese       

A．sing, dance and play cards

B．buy each other presents

C．never drinks

D．give each other the best wishes
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判断题

素描工具只局限于绘画铅笔和橡皮。
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