Question

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

Answer 1

D

解析:

“把書忘在辦公室”發生在“去取書”這一過去的動作之前，因此“忘了書”這一動作發生在過去的過去，用過去完成時。句中when表示的是時間的一點，表示在“同學們正忙于……”這一背景下，when所引導的動作發生。因此前一句應用過去進行時。