一、在英國英語中傳統(tǒng)上把used to看作是情態(tài)動詞,因此,它的疑問式應當是：Used ＋主語＋to sth．?否定式應當是used not to或use（d）n't to.但是,在美國英語中,人們把used to看作是實義動詞,因此,它的疑問式是：Did ＋主語＋use to do sth．?否定式是：主語＋didn't use．．．由于受到美國英語的影響,甚至在英國英語中,人們也很少使用“Used．．．＋主語＋to．．．”這種疑問式,而使用“Did ＋主語＋use．．．”這一疑問式.例如：
①Did they use to play football?他們過去踢足球嗎?
②Did you use to smoke?你過去吸煙嗎?
③Did you use to take long walks in the countryside?你過去在農(nóng)村經(jīng)常進行長距離的散步嗎?
二、在帶有used to的陳述句后面,附加疑問句中一般要使用功能詞did.但是,在附加疑問句中也可以用used.例如：
①He used to smoke,didn't he?
②They usedn't to like opera,did they?
They didn't use to like opera,did they?
They used not to like opera,did they?
③You used to live in Wuhan,usedn't you?
④You used to like wine,use（d）n't you?
三、used to的否定形式的一般問句常有以下兩種.例如：
Didn't you use to live near me?
Usen't you to live near me?你過去不住在我附近嗎?
四、used to指的是過去的習慣性動作,目的在于與現(xiàn)在形成對照,如：I used to work hard．是說“我過去常常努力工作.”暗含的意義是：我現(xiàn)在不努力工作了.在表示過去的習慣性這一點上,與would的意義相同（只不過used to既可用于表示過去的習慣動作,又可用于表示過去的狀態(tài).would只能用于表示過去習慣性的動作）.從形態(tài)上看used to是個情態(tài)動詞,其中的to是不定式符號,后面跟動詞原形.例如：
When I was a child,I would get up early．
People used to（不用would）believe the earth was flat．過去人們認為地球是平的.
I used to like swimming．
When I was a child,I used to（不用would）like swimming．
我哥哥過去是解放軍,現(xiàn)在是教師.
誤：My elder brother would be a PLA man．He is now a teacher．
正：My elder brother used to be a PLA man． He is now a teacher．
五、be（get,become）used to結(jié)構(gòu)在意義上相當于accustomed to“習慣于”,從形態(tài)上看,used是個分詞型形容詞,to是介詞,因此后面只能跟名詞、代詞或動名詞.例如：
They got used to living in the countryside．他們已習慣于住在農(nóng)村.
I've got used to being a vegetarian．我已經(jīng)習慣吃素食.
He is used to hard work．他習慣于艱苦工作.
六、be used to表示“習慣于某事”的狀態(tài),而get used to則表示由“不習慣”到“習慣于”這一動態(tài)的過程,意思是：“（變得）習慣于”；“開始習慣于”.試比較：
He was used to the cold weather after he lived there for two years．在那里住兩年后,他已習慣了寒冷的天氣.
I think it is a bit difficult for you to get used to the humid weather here．我想,讓你習慣于這里潮濕而炎熱的天氣有點困難.
You'll soon get used to living in the country．很快你就會習慣于住在鄉(xiāng)下了.
七、有時be used to是動詞use的被動語態(tài),在這種結(jié)構(gòu)里,to是不定式符號.例如：
A metal bar was used to force the door open．用金屬棒把門撬開.
The threshing ground was used to hold a mass meeting．打谷場曾用于舉行群眾大會.
八、be used to與be accustomed to的區(qū)別：前者一般用于指自然而然地成為習慣,后者常常用于指通過努力而成為習慣.試比較：
I am used to teaching English．我對教英語已習慣了.
Mrs Smith was not accustomed to leaving home during the winter．史密斯夫人不習慣冬天出門.
I am accustomed to taking coffee．我習慣了喝咖啡.