Cleaning and maintaining my house used to feel arduous and I oft

Cleaning and maintaining my house used to feel arduous and I often left tasks（ ）.
A、unfinishing
B、to finish
C、unfinished
D、finish
【正确答案】：C
【题目解析】：本题考查ed 分词做宾语补足语的用法，left tasks unfinished.