问题
选择题
下列关于重心的说法正确的是( ) |
A.重心是物体的各部分所受重力的合力的作用点 B.形状规则的物体的重心必与其几何中心重合 C.重心是物体上最重的一点 D.直铁丝被弯曲后,重心便不在中点,但一定还在铁丝上 |
答案
答案:A
下列关于重心的说法正确的是( ) |
A.重心是物体的各部分所受重力的合力的作用点 B.形状规则的物体的重心必与其几何中心重合 C.重心是物体上最重的一点 D.直铁丝被弯曲后,重心便不在中点,但一定还在铁丝上 |
答案:A
根据短文完成表格。每空不超过3个单词。 | ||||||||
I am near-sighted, and my eyesight is getting worse, because I play too many computer games and watch too much TV. I really play computer games a lot. There are so many different games and I spend all my time in playing them. When I play computer games, I always forget about my other plans. I am a bit ashamed (害羞) of this habit (习惯). I also like watching television. Sometimes I turn on my TV even while I am doing my homework. I usually sit one metre away from my TV and watch it for hours if my parents do not ask me to do something else. I know how bad my eyesight is when I am in a car. I look out of the window and see shops, but I can't see the signs clearly. I have to guess the shop names from from curves (弯曲物) and lines. I try my best not to wear glasses, because they change my appearance and make me look like a hen. I hate my eyes for making me wear glasses during school hours. I love my eyes at the same time because they let me see the beautiful world. Love your eyes and don't play too many computer games or watch too much TV. The world will be dark after you become near-sighted.
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