留不住的是人心BYK
Surface tension 表面张力Gas 气体 Within a liquid, the cohesive forces compensate each other and there is no resulting directed force 在液体内部，内聚力相互抵消，处 于力平衡状态 Liquid 液体In the liquid / gas interface, the cohesive forces are directed inwards and sidewards, resulting in a contracting force at this interface and leading to the spherical form observed 在 液/气界面，内聚力指向内里和侧面，在其界面产生 向内收缩的力，导致了球状的形成
