①【used to do sth.】：过去常常做某事（现在不做了） I used to go fishing everyday.
②【was used to do sth.是be used to do sth.的过去形式,用法一样】：某物被用来做某事 The pen is used to write letters.& The truck was used to transport goods.
③【be used for doing sth.】与上面的【be used to do sth.】都表示某物被用来做某事,只是介词不同 The pen is used for writing letters.
④【be used to doing sth.】表示习惯于做某事 I am used to getting up early in the morning.这个用法与【get used to (doing) sth.】的用法和意思一样,都表示习惯于做某事