I will come back after two o'clock.这句话里的after能不能换成at?为什么?最好举些例子,

您好,是可以的, 如果您确定返回的时间是两点整, 那麼是可以告诉他人: I will be back at two o'clock. 我两点钟会回来.如果是不切确时间, 但是会在两点後, 那麼一般是告诉别人, I will be back after two o'clock. ...