One of the reasons he explained to us was he had dreamt of doing so.A. why; thatB. that;

问题补充：

One of the reasons he explained to us was he had dreamt of doing so.

A. why; that

B. that; that

C. why; because

D. that; because

答案：

A. why; that

(答案→)B. that; that

C. why; because

D. that; because

解析：本题修饰短语one of the reasons是一个定语从句，现行词是物，可用关系词that，本题的后半句是一个宾语从句可用that来连接，故本题选B。