used to “过去常常”，仅用于过去时态中，通常用于所有人称。l
表示(用于过去持续或经常发生的事)曾经；
1、used to +动词原形，表示过去（有规律的）习惯或过去某一时期的的状况，但现在已不存在。
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 feel more compassion and less anger than I used to.
我觉得自己比过去多了些同情，少了些怒气。
I used to pour time and energy into projects that were doomed from the start.
我过去常常将大量时间和精力投入到从开始就注定要失败的计划中。
I used to stay up late with my mom and watch movies.
我以前总是和妈妈一起熬夜看电影。
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。( 否定式通常为didn't use to)
Did she use to have long hair?
她过去留长发吗？( 构成疑问句用did)
You used to see a lot of her, didn't you?
你过去常见她吧？
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。
Mum and I used to fall out a lot.
我和妈妈过去经常争吵。
另外，be used to doing (或直接接sth)指习惯于、适应于：
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。
I’m used to getting up early.
我习惯早起。
2、其反意疑问句简略回答中，也有两种形式：didn't ，use（d）n't
3、used to 和would的区别
（1）used to 可表示过去经常发生的动作或存在的状态，而would仅表示过去习惯性或重复性的动作。
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。
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。
（2）used to 强调过去的行为同现在的对比，含有“过去如此，现在已不再这样了”之意。Would仅表示过去习惯性动作，没有预先在对比的含义。
（3）used to不能跟表确定时间短的时间状语连用。
（4）used to 可用于无人称句和存在句，而would则不可。
4、used to与be used to do和be used to doing
（1）used to表示“过去常常”隐含现在不这样了，其中to是不定式符号，后跟动词原形，仅用于过去时态。
I used to take work home, but I don't do it any more
我过去常把活儿带回家干，不过我如今再也不这么做了。
I also used to love the smooth way in which the foreigner operated.
我也曾经喜欢那个老外平稳流畅的操作方式。
I used to come home and act out the movie for the kids.
以前到家后，我会把电影内容再表演给孩子们看。
（2）be/get/become used to 表示“习惯于”时，意为“变得习惯于“或“开始习惯于”。
Don’t worry─you’ll soon get used to his sense of humour.
别担心，你不久就会适应他的幽默感。
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。
Your immune system has been desensitized because it has become used to the substance.
你的免疫系统已经因习惯了这种物质而不再敏感。
We are a proud people. We are not used to begging or taking things.
我们是有自尊的民族。我们不习惯乞讨或接受施舍。
（3）be used to do表示“被用来”。
The new technique has been used to identify the sex of foetuses.
这一新技术已经被用来鉴别胎儿的性别。
Yoga can be used to strengthen the immune system.
瑜伽能增强人体免疫系统。
If necessary X-rays and blood tests will also be used to aid diagnosis
如有必要，还要进行X光检查和验血以帮助诊断。
Some of the guns were melted down and used to help build a statue
一些枪炮被回炉后用来建造了一座雕像。
Body language can also be used to attract members of the opposite sex.
肢体语言也可以用来吸引异性的注意。