问题补充：
I spent half an hour my homework.
A. finish doing
B. to finish doing
C. finishing to do
D. finishing doing
答案：
A. finish doing
B. to finish doing
C. finishing to do
(答案→)D. finishing doing
解析：句意是：我花了半个小时来完成家庭作业。有固定句式spend +doing sth 可知A和C 错误，由固定搭配finish+doing可知答案是D。
