钱大昕的生平简介。

答案:3 悬赏:0 手机版

解决时间 2021-04-02 20:10

提问者网友：锁深秋
2021-04-02 08:52

50字左右，急急急急急急急急急·································································································································································································································································································································································································································································································································

最佳答案

五星知识达人网友：纵马山川剑自提
2020-04-05 20:25

没看懂什么意思？

全部回答

1楼网友：夜余生
2020-07-30 14:57

这下我知道了

2楼网友：廢物販賣機
2019-07-05 13:32

解：图1：重力等于压力，只是作用点不同；
图2：重力大于压力，重力和压力的方向不同，作用点不同；
图3：重力不等于压力；
图4：重力和压力没有关系，重力竖直向下，压力垂直于接触面向右；
图5：重力不等于压力，重力竖直向下，压力垂直于接触面向上．
故

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