Question

The students _______ busily when Miss Brown went to get a book she _______ in the office

1. A.
   had written; left
2. B.
   were writing; has left
3. C.
   had written; had left
4. D.
   were writing; had left

Answer 1

D
考查时态。句意：当布朗小姐去取落在办公室的书的时候，学生们正忙于写作业。故第一空用过去进行时，第二空用过去完成时。选D。