“合力”造句
常规液体里分子之间的键
合力相对较弱。
The molecules in regular liquids are held together by relatively weak bonds.
粘阻力等于
合力.
The viscous drags is equal to the resultant force.
在这个和那个方向上的
合力必定为零.
The summations of forces in this and that directions must be zero.