used to指过去经常做某事或在过去某段时间里做过某事，含现在不再这样之意，强调今昔习惯的对比；此外，used to 除可后接动作性动词（如 work, eat, stay 等），也可后接非动作性动词（如 like, be, have等），以说明过去经常存在的情况或状态。
1.肯定式
I used to like pop music.我过去喜欢流行音乐。（现在已经不喜欢了）
We used to spend our vacations in the mountains.
我们从前在山区度假。（暗示现在已经不在山上度假了）
I used to live in London.
我曾经在伦敦居住过。
We used to go sailing on the lake in summer.
从前的夏天，我们经常泛舟湖上。
I used to go to the cinema every week.
我过去每周都去看电影。
People used to think the earth was flat.
人们曾经认为地球是平的。
All I know is that she used to work in a bank.
我只知道她曾在银行工作过。
Standards aren't what they used to be.
现在的行为标准和过去不一样了。
I used to smoke but I gave up two years ago.
我过去抽烟，但两年前就戒了。
I used to play here as a boy.
我小时候常在这里玩。
I used to love her but she's nothing to me any more.
我爱过她，但现在对她再也没什么感情了。
I used to enjoy gardening, but I don't have time for it now.
我过去喜爱园艺，但现在没时间去弄了。
We used to play hide-and-seek when we were children.
我们儿时常玩捉迷藏游戏。
He used to go to that private school.
他曾在那所私立学校就读。
2.否定式
I used not to like pop music.我过去不喜欢流行音乐。
I usedn’t to like pop music.
I didn’t use to like pop music.
I didn't use to like him much when we were at school.
以前我们同学时，我并不太喜欢他。
I used to smoke, but I gave up a couple of years ago.
我以前抽烟，但几年前就戒掉了。
I used to go there every Saturday.
我以前每星期六都去那儿。
3.疑问式
Used you to like pop music？ 你过去喜欢流行音乐吗？
Did you use to like pop music？
You used to go there，usedn’t you？ 你过去常到那儿去，是吗？
you used to go There,didn’t you？
You used to see a lot of her, didn't you?
你过去常见她吧？
Did she use to have long hair?
她过去留长发吗？
used to 的疑问形式用 did 构成，但此时要用 use to。
Did you use to go to church regularly?
你以前经常去教堂吗？
在否定句中用 didn't/did not use to 表示，也可用 never used to 表示。
She didn't use to eat meat.
她以前不吃肉。
They never used to ask what his favourite dish was.
他们以前从来不问他最喜欢吃什么菜。
在正式的英国英语中也可以说 used not to。
Planes used not to land here.
飞机以前不在这里降落。
4.used to与would的区别
（1）used to 与would表示过去习惯性的动作时，可互换。
When we were children we would/used to go skating every winter.
我们小时候，每年冬天都去溜冰。
He would/used to sit there for hours sometimes doing nothing at all.
有时他在那里一坐几个钟头，什么也不做。
would表示过去经常做某事，只强调过去的重复动作，而不能用于今昔习惯的对比，也不可后接非动作性动词。
His grandparents would take care of him when his parents were busy.
他父母忙的时候，总是祖父母照顾他。
On summer evenings they would have dinner in the garden.
夏天的晚上他们经常在花园里吃晚饭。
（2）若要强调过去与现在的对比时用used to。
I don’t smoke these days，but I used to.我现在不抽烟，但我以前是抽的。
I used to drive to work but now I cycle.过去我常开车上班，但我现在骑自行车。
【比较】
①People used to believe that the earth was flat.
过去，人们以为地球是扁平的。（现在已不再这样认为）
②He would go to the park as soon as he was free.
过去，他一有空就去公园。（现在有可能还去）
5.used to do，be used to 与be used to do的区别
（1）used to do 表示“过去常常”，现在已经不那样了。
He used to be a teacher in our school.他曾经是我们学校的一位老师。
There used to be an old temple near the village.过去村子的附近有一座古庙。
（2）be used to （doing）sth.表示“习惯于做某事”。
You soon get used to the little difficulties.
你很快就会习惯这些小小的不便了。
We're used to the noise from the traffic now.
现在我们已经适应车辆往来的噪音了。
You'll soon get used to the climate here.
你会很快习惯这儿的气候的。
He is used to hard work.他习惯于艰苦工作。
She was not used to mixing with people of high social rank.
她不习惯和社会地位很高的人搅和在一起。
He is used to living in the country.他已习惯于住在乡下。
I didn’t think I could ever get used to living in a big city after living in the country.
我觉得我在农村住了之后就无法适应大城市的生活了。
I’ve got used to being a vegetarian.我已经习惯吃素食。
I'm used to getting up early.
我习惯早起。
【提示】 be used to中be可用get，become替换，其中to是介词，后接名词、代词或动名词。
（3）be used to do表示“被用于做某事”。
Bamboo can be used to make a lot of things.竹子能被用来制成很多东西。
A hammer is used to drive in nails.锤子是用来钉钉子的。
Computer software can be used to simulate conditions on the seabed.
计算机软件可用于模拟海底状况。