A:石灰水
B:氢氧化钠溶液
C:硫酸
D:氨水
To _______ somebody to do something means to make somebody do something they don't want to do.
如图所示,独轮车车身及车上物品总重力G为300N,作用线如图,O点为车轴.将车把抬起时,作用在车把竖直向上的力至少为____N.独轮车属于____(选填“省力”、“费力”)杠秆.