Question

No one tells ________, so I need your help.

1. A.
   how should I do
2. B.
   what should I do
3. C.
   how to do it
4. D.
   what to do it

Answer 1

C
解析：
动词不定式和疑问词连用，当疑问词是what时，后面不需要宾语；当疑问词是how时，后面必须接宾语。