Question

---Has Tom finished his job yet?
---I have no idea of it; he _____ it this morning

1. A.
   has been doing
2. B.
   had been doing 　
3. C.
   did 　　
4. D.
   was doing

Answer 1

D
考查时态。表示过去某一时刻正在进行的动作用过去进行时态。句意：汤姆完成他的工作了吗？我不清楚，他整个上午一直在做。所以选D。