Question

The clever boy made a hole in the wall，_______ he could see what was going on inside the house. A.

The clever boy made a hole in the wall，_______ he could see what was going on inside the house.
A. by which
B. by that
C. through which
D. of which

Answer 1

句子拆分：
The clever boy made a hole in the wall
He could see what was going on inside the house through the hole

由此可见：
介词用的是through
定语从句中的 which 指代a hole

综上，选C

Answer 2

C through which 是通过某种物质来。。。

Answer 3

C
through透过孔洞

Answer 4

选择C，因为通过那个洞看里面发生的事