1、used to do sth,意为过去常常做某事,现在已经不再做了。例句：I used to play football after school.过去我常常在放学后踢球。2、be/get used to doing sth,意为现在习惯做某事。例句：I am accustomed to the weather here.我已经适应了这里的天气了。3、sth be used to do ,意为某物被用来做某事。例句： Wood is used to make paper.木头被用来造纸。