This is the present perfect, which is constructed using: What happened还是what's happenedwhat happened和what's happened都用于询问过去发生了什么事情，主要的区别在于语法和使用方式。what happened是一个过去时态的简单 Here, what's is the contraction of what has.
Arrest made in fatal Danville shooting FOX 56 News
The helping verb have 2.
What happened 和 what's happened两者的区别： 是问 what happened？只是想知道过去所发生的事情， 而如果用what's happened？则强调对现在的影响。，即想知道过去所发生的什么事.
接下来让我们看下what happen和what happened的用法区别： 1.词性：what happen是用原形动词happen构成的现在时短语，而what happened是用动词happen的过去式happened构成的过去. What happened?和what's happening?的区别是什么？what happen?表示发生了什么，用于询问发生了什么事情，通常用于过去的事件或突发情况。而what’s happening?表示正在发生什. 'happend' is a spelling mistake of happened. 接下来让我们看下what happen和what happened的用法区别： 1.词性：what happen是用原形动词happen构成的现在时短语，而what happened是用动词happen的过去.
