Susan decided not to work on the program at home because she didn’t’ want her parents to k

问题补充：

Susan decided not to work on the program at home because she didn’t’ want her parents to know what she .

A. has done

B. had done

C. was doing

D. is doing

答案：

A. has done

B. had done

(答案→)C. was doing

D. is doing

解析：考查动词的时态。因为主语的工作当时尚未完成，又处于过去的时间背景当中，所以采用过去进行时态。