used to do, be used to do 和be used to doing用法区别：
used to是情态动词，后接动词原形
1.used to do sth. 过去常常做某事 (现已不做)
肯定句：主语+ used to do
否定句：主语+ didn't + use to do
一般疑问句：Did+主语+use to do 
特殊疑问句：What + did+主语+use to do?  

His father used to smoke.  
他爸爸之前经常吸烟。
→His father didn't use to smoke.
→Did his father use to smoke?
→What did his father use to do?


2.be used to doing sth. 习惯做某事
He is used to living alone.
他习惯一个人住。
They are used to listening to English songs.
他们习惯了听英文歌。
He is used to eating meat.
他习惯吃肉了。

3.used to与动词use各种搭配区别
  

I used to go shopping with Amy.
我过去常常和艾米一起逛街。
He used wood to make a fire.
他用木头生火。
The wood was used to make a fire.
木头被用来生火。
The wood was used for making a fire.
木头被用来生火。