When using 'how come' you are asking why a particular thing has or had to take place.
当使用'how come'的时候，你在问为什么一个特定的事会发生或者已经发生。

Here are some examples: 这里有一些例子：

"How come parents worry so much?" 

为什么父母如此担心？

"How come people carpool to work?" 

为什么人们拼车上班？

"How come you are so upset?" 

你怎么会这么难过？

"How come he will not call you?" 

他怎么会不给你打电话？

"How come you stayed out so late?" 

为什么你在外面待这么晚？

"How come you cannot make a decision?" 

你为什么不能做一个决定？

"How come you always question me?" 

为什么你总是问我？

"How come we never agree?" 

为什么我们从不同意？

"How come your dog digs in the yard?" 

为什么你的狗在院子里挖洞？

"How come she will not come over?" 

她怎么会不来呢？