题目内容：

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

优质解答

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.