how come you look so tired.come 是怎么回事和do 一样吗
问题描述：
how come you look so tired.come 是怎么回事和do 一样吗
答
how come是固定短语,为什么; 怎么会…(那样) .
这里come不能换成do.How do you look so tired句意不通.
How come you look so tired相当于Why do you look so tired或How are you.