Ann, can you see what is happening there.这句话有错吗？宾语从句不是要主谓语序吗？

这句话没错．
I don't know who he is.
这是主谓正常的．宾语从句中不缺少主语．
He is running.
I know who is running.
Mr Smith is killed in the accident.
I know who is killed in the accident.
我们可以发现，宾语从句的引导词实际上是在从句中占一个语法位置的．例句一中，who代的是人，但做的是从句宾语．
例句二和三中，who代的也是人，但它是从句实际的主语．
what在你的句中也是这样，它就是主语．
换个方式，也许好理解．
Something is happening there.
Can you see what is happening there?

没有错,因为这个WHAT做了主语,就不用换语序,
当疑问词,想WHAT WHERE,HOW,WHAT TIME.....等等做了主语是就不用换语序了,呵呵