急!求be used to do be used to doing used to doing be used for doing 的区别以及用法

题目

急!求be used to do be used to doing used to doing be used for doing 的区别以及用法

答案

sth be used to do be used for doing 某物被用于做某事
be used to doing 习惯做某事
used to do 过去常常做某事