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问题 选择题

{an}为等差数列，Sn为其前n项和，a7=5，S7=21，则S10=（　　）

A．40

B．35

C．30

D．28

答案

由题意可得，

a1+6d=5
7a1+21d=21

解可得a1=1，d=

2
3

∴S10=10×1+

10×9
2
×
2
3
=40

故选A

填空题

用延续性动词改写下列句子。

1. The man has left China. The man has _____ _____ _____ China for 20 years.

2. The movie has finished. The movie has _____ _____ for half an hour.

3. I have borrowed the book. I have _____ the book for a month.

4. He has joined the Party. He has _____ _____ the Party for 30 years.

5. I have bought the bike. I have _____ the bike for 6 years.

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单项选择题

有关术前准备，不正确的是

A．医护人员向病人及家属介绍病情及治疗方案

B．练习床上排便、排尿

C．提前2周戒烟

D．练习正确的咳嗽，咳痰方式

E．提前3周预防性应用抗生素
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