问题
选择题
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
答案
答案：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。