Question

The students _____ busily when Miss Brown went to get a book ____ 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

 

第一個空表示動作正在進行；第二個空表示的動作發(fā)生在第一個動作之前。