The students busily when Miss Brown went to get a book she in the office.
A. had written; left
B. were writing; has left
C. had written; had left
D. were writing; had left
网友回答
A. had written; left
B. were writing; has left
C. had written; had left
(答案→)D. were writing; had left
解析：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。