how come?

used to ask how or why something has happened

为什么?怎么会?

How come 的用法大部分就等于 why ，但是它的用法没有像 why 那么广, 它通常是用在你觉得奇怪, 而问为什么的时候。

So how come you missed the train?

你们怎么会误了火车?

Laura, it seems that you are up to your neck in work, how come you've been so busy?

劳拉，你的工作似乎忙得不可开交，你怎么这么忙?

A：We had to stop in Birmingham.

我们必须在伯明翰停留。

B：How come?

为什么?