问题补充：
Please at once after all of you have finished your homework.
A. hand them out
B. hand them in
C. hand it in
D. hand it out
答案：
A. hand them out
B. hand them in
(答案→)C. hand it in
D. hand it out
解析：句意：请在你们都完成家庭作业后，马上交上。homework 为不可数名词，应该用it代替。hand in上交；hand out伸出。选C。
考点: 考查动词短语的用法。
