They __________tennis together when they were at college.

问题描述:

They __________tennis together when they were at college.
used to play
were used to play
used to playing
are used to playing

答案:A used to play
used to do sth...
表示以前做什么,现在不做了.
B,C 语法不对.
D 是说 他们现在很习惯于做怎么.但是跟后面的从句表达的时间不符.