If anything dangerous _______ (happen), you can find them easily.答案是happens,那这和 What's happened 有什么区别呢?

问题描述:

If anything dangerous _______ (happen), you can find them easily.
答案是happens,那这和 What's happened 有什么区别呢?

对于定理,经常发生的事情用一般现在时,也就是happens,对于过去发生的事情,提问时用happend表示已经过去的事情。

条件状语从句,用一般现在时表示
What has happened代表名词,可以作主语或宾语成分.