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如图所示,光滑水平面右端B处连接一个竖直的半径为R的光滑半圆轨道,B点为水平面与轨道的切点,在离B距离为x的A点,用水平恒力将质量为m的质点从静止开始推到B处后撤去恒力,质点沿半圆轨道运动到C处后又正好落回A点.试求:

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同类题5

假定你是中学生李华。在一位名叫TigerMom的学生家长的博客上,你看到如下内容。请你根据博客内容、写作要点和要求,给这位家长回复。

    I'm the mother of a fourteen-year-old. I have a rule for my daughter: be among the top 5 students or get punished in one way or another. She has been doing very well in school, but some friends of mine keep telling me that I put too much pressure on her. Am I wrong?

写作要点:

1)表明自己的看法;

2陈述自己的理由(可举例说明);

3)提出至少两条建议。

要求:1)短文词数100左右。

2)内容充实,结构完整,语意连贯。

Hi, TigerMom,

    What puzzles you is actually a puzzle for many parents in China. My idea is



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                                                                                                                                                                                                  LiHua