问题
选择题
如图所示,甲、乙两体在冰面上“拔河”。两人中间位置处有一分界线,约定先使对方过分界线者为赢。若绳子质量不计,冰面可看成光滑,则下列说法正确的是( ) |
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A.甲对绳的拉力与绳对甲的拉力是一对平衡力 B.甲对绳的拉力与乙对绳的拉力是作用力与反作用力 C.若甲的质量比乙大,则甲能赢得“拔河”比赛的胜利 D.若乙收绳的速度比甲快,则乙能赢得“拔河”比赛的胜利 |
答案
答案:C
如图所示,甲、乙两体在冰面上“拔河”。两人中间位置处有一分界线,约定先使对方过分界线者为赢。若绳子质量不计,冰面可看成光滑,则下列说法正确的是( ) |
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A.甲对绳的拉力与绳对甲的拉力是一对平衡力 B.甲对绳的拉力与乙对绳的拉力是作用力与反作用力 C.若甲的质量比乙大,则甲能赢得“拔河”比赛的胜利 D.若乙收绳的速度比甲快,则乙能赢得“拔河”比赛的胜利 |
答案:C
We live in computer age (时代). People scientists, teachers, writers and even students use computers to do all kinds of work. But more than 30 years ago, couldn't do much. They were very big and expensive. Very people were interested in them and knew how to use them. Today computers are smaller and , but they can do work than before. Many people like to use them. Some people even have them at home. Computers become very important because they can work than people and make fewer mistakes. Computers can people do a lot of work. Writers now use computers to . Teachers use them to help teaching. Students use them to . Computers can also remember what you them. Computers are very useful and helpful. They are our friends. Do you want to have a computer?
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