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问题 选择题

如图，长为2L的直导线折成边长相等的直角形状，并置于与其所在平面相垂直的匀强磁场中，磁感应强度为B，当在该导线中通以电流I时，该直角形通电导线受到的安培力大小为（　　）

A．0

B．BIL

C．

2
BIL

D．2BIL

答案

导线在磁场内有效长度为l=

2
L，故该L形通电导线受到安培力大小为：F=BI2•
2
L=
2
BIL，选项C正确．

故选：C．

填空题

根据句意及首字母或汉语提示完成单词

1. The sweater is too large.  It doesn't f____ my father.

2. You should not feel under p____.You  should relax yourself.

3. We go to work every day e____ Sunday.

4. Teenagers should have more______ （自由）,and they should have their own ideas.

5. My job doesn't____（包含）making coffee  for the boss.

6. They are ________(plan) how to spend the summer holiday.

7. I couldn't believe my ear when my teacher  told me I ____(fail) the exam.

8. That news_________. (surprise) me a lot, because I didn't think he was careful.

9. Their _____(push) parents always let them   take part in so many after-school clubs.

10. You should be ______ (friend) if you want to  be popular.
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选择题

西藏解放60年来，为帮助西藏经济社会发展，国家在经济建设和财政支出上加大支持力度，重视发展西藏的民族文化教育，西藏自治区呈现出民族团结和睦、社会和谐发展的局面。这说明

①加快少数民族地区发展是推动民族问题解决的重要途径

②各民族共同繁荣为民族平等和民族团结提供了物质保证

③加大对民族地区的扶持是推动民族地区发展的根本动力

④各民族共同繁荣是实行民族区域自治制度的核心

A．①②

B．③④

C．②③

D．②④
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