used to （只有過去時形式，沒有現(xiàn)在時形式）表示過去習
    慣動作或狀態(tài)，這種情況現(xiàn)已不復存在。例如：
    He used to smoke a lot， but he has long given up smoking.
    在否定陳述句或否定疑問句中，用didn't use to或used't to均可：
    He didn't use to smoke cigarettes.
    He used't to smoke cigarettes. 
    Didn't Maria use to be interested in the theatre？
    Used't Maria to be interested in the theatre？ 
    在肯定疑問句中也可有兩種形式：
    Used you to go to the same school as Edward？
    Did you use to go to the same school as Edward？ 
    近義詞辨析
    use， apply， avail， employ， utilize
    這組詞均含有“使用”或“利用”之意。
    use
    強調(diào)利用人或物作為工具。
    He used up all his resources in experimenting with the new paint.他為實驗新的涂料，花光了一切錢財。
    apply
    指把某物或某種方法、原理等加以應用。
    We should not only know the theory but also know how to apply it to practice.我們不僅要知道理論，還要知道怎樣把理論應用于實踐。
    avail
    指使用就近的或他人給予的東西，或使別人為自己提供服務。
    I don't think complaints will avail you much.我覺得抱怨對你沒多大用處。
    We avail ourselves of every opportunity to speak English.我們利用一切機會講英語。
    employ
    指使用未被利用的東西；用于人時表示雇用。
    He does't know how to employ his energy and time.他不知道該怎么利用他的精力和時間。
    utilize
    指充分發(fā)揮某物的作用，使無用的東西變有用，或使人或物有新用途。
    She hopes to utilize her artistic talents in the job.她希望在工作中發(fā)揮她的藝術才能。