GbEng
怎么回事?你为什么哭? What's the matter? Why are you crying?
他们两人并不知道这回事, 因此一定是另外有人泄露了秘密. Neither of them knew about it, and the corollary of that is that someone else revealed the secret.
在打斗中为了自卫把人打死是一回事,残酷无情地开枪杀人是另一回事。 It's one thing to kill a man in a fight, in self-defence, another to shoot him in cold blood.