[
used to + 动词（ VERB ） ] 例句（ Examples ）：
I used to go to the beach every day.
最好不要在疑问句或否定形式中使用 used to； 然而，这有时是用非正式的英语口语来完成的。 最好使用一般过去时（ simple past ）来提问并创建否定句。
It is better not to use used to in questions or negative forms; however, this is sometimes done in informal spoken English. It is better to ask questions and create negative sentences using simple past.
过去的习惯（ Habit in the Past ）
Used to expresses the idea that something was an old habit that stopped in the past. It indicates that something was often repeated in the past, but it is not usually done now.
Used to 用于描述过去停止的旧习惯。 它表示过去经常重复某件事，但现在通常不这样做。
例句（ Examples ）：
Jerry used to study English.
Sam and Mary used to go to Mexico in the summer.
I used to start work at 9 o'clock.
Christine used to eat meat, but now she is a vegetarian.
过去的事实和概括 （ Past Facts and Generalizations ）
Used to can also be used to talk about past facts or generalizations which are no longer true.
Used to 也可以用来谈论过去的事实或不再正确的概括。
例句（ Examples ）：
I used to live in Paris.
Sarah used to be fat, but now she is thin.
George used to be the best student in class, but now Lena is the best.
Oranges used to cost very little in Florida, but now they are quite expensive.
Used to vs. 一般过去时（ Simple Past ）
Both simple past and used to can be used to describe past habits, past facts and past generalizations; however, used to is preferred when emphasizing these forms of past repetition in positive sentences. On the other hand, when asking questions or making negative sentences, simple past is preferred.
一般过去时（ simple past ）和 used to 都可以用来描述过去的习惯、过去的事实和过去的概括； 然而，当在肯定句中强调这些形式的过去重复时， used to 是首选。 另一方面，在提问或造否定句时，一般过去时（ simple past ）是首选。
例句（ Examples ）：
You used to play the piano.
Did you play the piano when you were young?
You did not play the piano when you were young.
主动（Active）和被动（Passive）
例句（ Examples ）：
主动（Active） Jerry used to pay the bills.
被动（Passive） The bills used to be paid by Jerry.
