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问题 计算题

一根2米长的硬杆AB水平放置，A端挂30N的物体，B端挂50N的物体，要使杠杆平衡支点应距A端多远？若两端各增加10N的物体，为使杠杆平衡，支点向何方移动多少米？

答案

解：

A端挂30N的物体，B端挂50N的物体

∵ F1L1=F2L2

30NL1=50NL2

∴ =

∴ L1=×AB=×2m=1.25m

两端各增加10N的物体

∵（30N+10N）L1=（50N+10N）L2

∴=

∴ L1=×AB=×2m=1.2m

所以应向A端移动1.25m﹣1.2m=0.05m

改错题

七、短文改错（共10小题; 每小题0.5分，满分5分）

假如英语课上老师要求同学们交换修改作文，请你修改你同桌写的以下作文。文中

有10处错误，要求你在错误的地方增加、删除或修改某个单词。

增加：在缺词处加一个漏字符号(∧)，并在其下面写上该加的词。

删除：把多余的词用斜线(＼)划掉。

修改：在错的词下划一横线，并在该词下面写上修改后的词。

注意：1. 每处错误及其修改均仅限一词。

2. 只允许修改10处，多者(从11处起)不计分。

Last summer vacation, I worked as a volunteer in a hospital, where I meet a little girl, Rosalyn, who was near eight years old. She just had operation in her leg but had to stay in bed for some time. I was amazing by her courage because she never cried even if she was suffered a great deal of pain. I once noticed her helping a little boy which parents couldn’t come to see him that day. She was sharing her sweets and toys for the boy and telling stories to calm him down. Soon she stopped crying. I wondered that if many grown-ups could be as kind as she was to others!
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单项选择题

既可用于热淋、砂淋、石淋；又可用于恶疮肿毒、毒蛇咬伤的药物是（）

A.泽泻

B.冬葵子

C.车前子

D.金钱草

E.猪苓
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