Question

He did ________ he could help me with my maths.

1. A.
   what
2. B.
   that
3. C.
   which
4. D.
   that what

Answer 1

A
题中的宾语从句中省略了动词do。连接代词that和what都能引导宾语从句，但that只能起连接作用，无具体意义；而what主要用于代替物体，既可以引导宾语从句，又在从句中作省略了的动词do的宾语，与句意和结构相符，故答案为A。