used to do 过去常常做.
be used to doing 习惯做.
be used to do sth 被用来做某事
be used for doing sth 被用来做某事
keep doing sth 坚持做某事
keep on doing sth 一直做某事
used to do 过去常常做.
be used to doing 习惯做.
be used to do sth 被用来做某事
be used for doing sth 被用来做某事
keep doing sth 坚持做某事
keep on doing sth 一直做某事