序数词的用法（序数词的基本用法）

He ran the third fastest in his class.

5月5日

Li Lei&39;s second book is old.

部分分数可以使用 half 和 quarter。

He was second in the exam.

序数词前也可以使用a或an, 表示的含义是“又一，再一”，常常有语言环境；

写作：May 5, May 5th, May the fifth, 5 May, 5th May

第一次 for the first time

三分之一 one third

读作：May (the) fifth, the fifth of May

三分之二 two thirds

带分数: 整数+分数

The long river is the second longest river in China.

母序子基 : 即分母用序数词，分子为基数词，分子大于1，分母加－s.

two and three fourths

四分之三 three fourths =three quarters

The first student to come to school is usually Jim.

He is my first English teacher.

首先 first of all

They have two children, and next year they will have a third child.

序数词的用法在初中阶段很重要，也是考试中的高频考点，现将其用法汇总如下：

二分之一 one second=a half

四分之一 one fourth=a quarter

起初 at first