I__________ swim in summer when I was young.

I__________ swim in summer when I was young.
A、used to
B、used
C、was used to
D、did used to
【正确答案】：A
【题目解析】：句中的时间状语是when l was young，表示过去，因此应选A项。“used to+动词原形”意为“过去常常做某事(而现在不做了)”。