—Our class will have a party the evening of June 30th. Would you like to come? —Yes, I'd love to, but I'm going to visit my grandparents in Dalian.
如图所示,质量为M=60kg的人站在水平地面上,用定滑轮装置将质量为m=20kg的重物送入井中.当重物以2 m/s2的加速度加速下落时,忽略绳子和定滑轮的质量及定滑轮的摩擦,则人对地面的压力大小为(g取10 m/s2)( )
如何正确评价洋务运动?