【题目】I'll 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】B
【解析】句意：一完成手头的工作我就去图书馆。根据主句和从句中的时态排除A项和D项；根据句意排除C项。故只有B项符合题意。