问题补充：
The old man us interesting stories when we were young.
A. were used to tell
B. used to tell
C. got used to tell
D. used to telling
答案：
A. were used to tell
(答案→)B. used to tell
C. got used to tell
D. used to telling
解析：从时间状语从句when we were young得知,主句的时间应用过去时, used to do意为:过去常常.
