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
D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。