说明原因 I wrote a letter to the car dealer,__what had happened to my new car.
问题描述：
说明原因 I wrote a letter to the car dealer,__what had happened to my new car.
A.explaining
B.to explain
C.explains
D.explained
答
A
B 表目的时不能和主句用逗号分离
C 完全不对,单独做句子没主语,做附加成分不可以用一般时,也不可能加S
D 表示主语与后面动词explain是被动关系才用 过去分词.