The wrong youve done to him is terrible for you should make an apology to him I think.

问题补充：

The wrong youve done to him is terrible, for you should make an apology to him, I think.

A. this

B. which

C. what

D. that

答案：

A. this

(答案→)B. which

C. what

D. that

解析：此题还是考查非限定性定语从句，which替代for前面的句子。