序数词的用法（序数词的基本用法）

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

首先 first of all

He is my first English teacher.

三分之二 two thirds

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.

三分之一 one third

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；

读作：May (the) fifth, the fifth of May

四分之一 one fourth=a quarter

部分分数可以使用 half 和 quarter。

The first student to come to school is usually Jim.

二分之一 one second=a half

5月5日

四分之三 three fourths =three quarters

第一次 for the first time

起初 at first

He ran the third fastest in his class.

two and three fourths

He was second in the exam.

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

Li Lei&39;s second book is old.

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：

The long river is the second longest river in China.

带分数: 整数+分数