When he was young,he ______ the old man.A.used to call on B.used to call
问题描述：
When he was young,he ______ the old man.A.used to call on B.used to call
A.used to call on B.used to calling on C.was used to call on D.was used to calling on
答
A 当他年轻的时候,经常拜访老人.use to do sth.过去常干某事,现在不做了.
use to doing sth.习惯做某事