I'll go to the library as soon as I finish what I .A. was doingB. am doingC. have doneD.

问题补充：

Ill go to the library as soon as I finish what I .

A. was doing

B. am doing

C. have done

D. had been doing

答案：

A. was doing

(答案→)B. am doing

C. have done

D. had been doing

解析：考查时态题。as soon as 后的从句用的是现在时态，排除AD，finish后的宾语从句是用现在时态，排除C。B项表示手头正在做（还没完成的）。句子意思：一完成我正在做的工作，我就会去图书馆。