否定式

He used not/ usedn’t to smoke cigarettes.

He did not/ didn’t use to smoke cigatettes.

疑问式

Used he to smoke cigarettes?

Did he use to smoke cigarettes?

used to be/do sth 过去常常做某事

be used to do sth 被用于做某事

be/get/become used to doing sth.习惯于…

区别

Tom used to go to the cinema. A knife is used to cut bread. She is used to living in the country.

汤姆过去常常看电影。

小刀被用来切面包。

她习惯于住在农村。