序數(shù)詞在句中可用作下列各個(gè)句子成分：
1)主語(yǔ)
The first is better than the second.第一個(gè)比第二個(gè)要好。
2)賓語(yǔ)
He was among the first to arrive.他是首批到達(dá)的。
3)定語(yǔ)
China exploded its first atom bomb in October 1964.中國(guó)于1964年10月爆炸了第一顆原子彈。
His father died in the Second World War.他父親在第二次世界大戰(zhàn)中死去。
4)表語(yǔ)
Jack is always the first to get to the office in the morning.杰克每天早晨總是第一個(gè)到辦公室。
[注]序數(shù)詞前面常用定冠詞the。
分?jǐn)?shù)和小數(shù)的讀法
1)分?jǐn)?shù)(fraction)分子為基數(shù)詞，分母為序數(shù)詞并有復(fù)數(shù)。
1／2 one half [hB:f]； 1／3 one-third； 2／3 two-thirds；
1／4 one-fourth或 one quarter [5kwC:tE]； 3／4 three-fourths或 three quarters； 2 3/5 two and three-fifths.
2)小數(shù)(decimal)
0.5 zero [5ziErEu] point five； 1.25 one point two five； 3.458 three point four five eight.