---What do you think of my suggestion?--- Sorry. What's that? I about something else.A.

问题补充：

---What do you think of my suggestion?

--- Sorry. Whats that? I about something else.

A. thought

B. am thinking

C. was thinking

D. had thought

答案：

A. thought

B. am thinking

(答案→)C. was thinking

D. had thought

解析：本句意为我刚才正在想别的事，故为过去时态。