used to do和be used to do

used to do过去常常做某事
He used to swim every day.他过去每天都游泳。（现在不是了）

be used to do被用来做某事，use sth to do的被动形式
Petroleum can be used to produce various chemical products.石油可用于生产多种化学产品

used to do 过去常常
I used to meet my teacher.
be used to do 被用来做...
Pen is used to write.

1，习惯于\过去常做某事
He used to read Englishbook.
2，被用于做某事
The rest milk is used to wash face.

used to过去常常;以前常常（后接不定式，表示过去的习惯）
He used to play badminton every day
be used to 习惯于做某事后+doing
I am used to playing football.
注明：be used to do 做被用来干某事的意思时，后就跟动词原形了，要看具体的意思