这几个词组有什么不同?(英语)

问题描述:

这几个词组有什么不同?(英语)
(1) be used to do sth.
(2) be used to doing sth.
(3) used to do sth.

(1) be used to do sth.被用来做某事
(2) be used to doing sth.习惯于做某事
(3) used to do sth.过去常常做某事