I think they failed to accomplish the task ?A. do IB. dont IC. did theyD. didnt they

问题补充：

I think they failed to accomplish the task, ?

A. do I

B. don I

C. did they

D. didn they

答案：

A. do I

B. don I

C. did they

(答案→)D. didn they

解析：当主句的主语是第一人称时，反问部分要和从句主语保持一致，还要注意否定的转移。