1.序數(shù)詞主要用作定語(yǔ)，前面一般要加定冠詞(或物主代詞)：
    Tom is their second son.
    They celebrated the 10th anniversary of the founding of the republic.
    I will never give up, not even on the 1,000th or 10,000th try.
    2.有時(shí)前面可以加一個(gè)不定冠詞來(lái)表示“再一”， “又一”這樣的意思：
    We’ll have to do it a second time.
    Shall I ask him a third time?
    When I sat down, a fourth man rose to speak.
    3.First,second 等有時(shí)可用來(lái)表示“第一個(gè)人(批)”“第二個(gè)人”等：
    She was among the first to come and settle in Dujiashan.
    You will be the second to speak.
    4.如果數(shù)字較長(zhǎng)，序數(shù)詞總避免使用，而且讀的方法也常常簡(jiǎn)化：
    第201房間：　Room 201
    第319面：　page 319
    第一拖拉機(jī)廠：the Number I Tractor Works
    第六號(hào)車廂：Carriage No.6
    南京路1490號(hào)：1490 Nanjing Road
    電話號(hào)碼55――2347：telephone number : 55—2347
    5. 在談編了號(hào)的東西時(shí)，我們可以用基數(shù)詞表示順序：
    the first part------part one
    the third squad------squad three
    the twenty-third section----section twenty-three