how time flies 中flies是fly的单三形式还是名词复数形式,为什么?

how time flies 中flies是fly的单三形式还是名词复数形式,为什么? How time flies(fly)! time flies how time fly 到底应该是How times fly 还是 how time flies? time flies fast还是time fly fast time fly和time flies的区别 How time flies!Three years ( )really a short time 是was还是is 三 how quickly time flies!这里flies为什么不用原型呢? how time flies How time flies!是什么意思? 到底是time flies还是time files How time flies 是个什么句型