used to do是过去常常做某事
used doing是习惯于做某事
I used to do it all the time.
我以前都是这样的。
You used to do this by yourself?
以前都是你自己一个人做的吗?
People here are used to doing for themselves.
这里的人对自救已经习惯了。
I'; m not used to doing it in this way.
我不习惯于这样的做法。