问题补充：
The teacher requested that they their homework on time.
A. finished
B. could finish
C. finish
D. would finish
答案：
A. finished
B. could finish
(答案→)C. finish
D. would finish
解析：句意：老师要求他们按时完成作业。request要求；在表示建议、命令、要求、忠告等动词的后面的宾语从句中的虚拟语气由于这些动词本身隐含说话者的主观意见，认为某事应该或不应该怎样，这些词语后面的“that”从句应用虚拟语气，且均以“should+动词原形”表示这种语气，但事实上“should”常被省略，故此从句中谓语动词用原形。故选C。
