1．used to可看作一个半助动词或情态动词，其后跟动词原形，表示过去的习惯或经常发生的动作，例如：
When he was a child, he used to ask lots of questions.
I want to know the places (that/which) he used to go to.
否定式为：used not to(书面语), use(d)n’t to(口语), didn’t use to(口语)
疑问式为：Used sb to …?(书面语), Did sb use to …?(口语)
反意疑问句式为：use(d)n’t sb? (书面语) didn’t sb? (口语)
2．be used to = get used to 都是一个固定的结构，意思为：习惯于某事或做某事的意思，to为介词，后接名词或动名词，不能跟动词原形，例如：
We are used to the weather in the south of China.
They have got used to getting up early in the morning.
be used to的各种形式变化如下：
疑问式为：Be(具体形式) sb ….? 否定式为：sb be(具体形式) not …
反意疑问式为：be(具体形式) not sb? （be作为系动词看待）
get used to的各种形式变化如下：
疑问式为：Do/Does/Did sb get …? 否定式为：sb does/do/did not get …
反意疑问式为：do/does/did not sb? （get作为行为动词看待）
3．be used to + Verb或as/for接名词，表示某东西被用来作某事或当什么东西来使用，是一个被动语态的结构，例如：
This knife is usually used to cut fruit.
This magazine was used as a fan last night because of the hot weather.
Blooms are used for cleaning the floor when we do general cleaning.
由于be为助动词，因此它的疑问式、否定式及反意疑问式则按一般规则进行变化。
注意used to与would的区别：
(1)．used to重在表示与现在的对比，含“过去曾经/一度，现在未必”之意；would重在叙述过去的情况，没有上述含义。如可以说：
He used to get up early, but not now. 但不说：He would get up early, but …
(2)．used to可以表示过去习惯或经常的状态；would不能，它只能表示过去的一个经常重复的动作，如可以说：
There used to be a temple nearby. 但不能说：There would be …
(3)．used to较正规、普通，多用于口语；would不太正规、多用于书面语。
(4)．两者都不能用于表示某事发生的具体次数。但would可表示过去有时或偶尔发生的动作，因而可与sometimes, now and then, from time to time等时间状语连用，例如：
He would sit there for hours sometimes, doing nothing at all.
补充练习：用used to, be/get used to填空：
1．I am surprised to see you smoking; you didn’t _______________ .
2．There ________________ be a station here, didn’t there?
3．He ______________ living in the country.
4．This book _____________________ be very popular.
5．It _________ not ___________ be so cold in winter in former years.
6．I _______________ these cigarettes now that I can’t enjoy any others.
7．People ____________________ think that the earth was flat.
8．__________ you ______________ swim every day when you were children?
9．It’s hard to understand him if you _________ not _____________ their accent.
10． He __________ not ___________ being treated like that.
11． Dictionary can’t ___________________ to learn English well in class but __________________ a tool to help you with your English.
12． Recorders ________________ for playing tapes in the English class now.
Key: 1. use to 2. used to 3. (has) got/is/was used to 4. used to 5. used, to/did, use to 6. am used to/ have been/got used to 7. used to 8. Used, to/Did, use to 9. are, used to/do, get used to
10. is, used t/does, get used to 11. be used, (can be used) as 12. are used （有的答案不止一个）