Question

Do you know____?A.what he happenedB.what the matter is with himC.what happened to him

Answer 1

你好！
B
what
is
the
matter
with
him
A
he
和happen
搭配完全不对么。
仅代表个人观点，不喜勿喷，谢谢。

Answer 2

选C；
A中he
和happen
是不能放在一起的，你犯了一个中文中典型的错误，发生了什么，happen是表示事情的发生，只能与有关事情的单词，
如果你要表达他怎么了，应该是What
happened
to
him。
至于B，应改为What
is
the
matter
with
him
，说到这里你应该知道了happen和matter一样需要与what，it等关于事情的单词。