序数词在句子中同样可以做很多种成分，序数词数词在句中可用作主语、表语、宾语、定语、同位语、状语等。如：

1.It’s said that 13 is an unlucky number.
1.据说13是一个不吉利的数字。

2.He was the first man to think of it.
2.他是第一个想到这一点的人。

3.The town is 2,000 feet above sea level.
3.这座城市海拔2,000 英尺。

4.Who is that man, the first in the front row?
4.前排第一个是准？

5.Mrs. Brown was about to begin, but Jennie spoke first.
5.布朗夫人正要开始讲话，珍妮先讲了。

6.I want the third, because the first two look a bit small.
6.我想要第三个，因为前面两个看上去小了点。

7.Tom is the third man that she was married to.
7.汤姆是她的第三任丈夫。

8.We are to carry out the first plan.
8.我们将要执行第一套计划。

9.I am the first in our class.
9.我是我们班第一名。

10.We'll go over it a second time.
10.我们将再次超越它。

11.We've tried it three times．Must we try it a fourth time?
11.我们已经尝试过三次了，还有必要尝试第四次吗？

12.Mother was my first teacher in my life.
12.妈妈是我生命中的第一位老师。

13.One fifth of the students here are from the country.
13.五分之一的学生来自那个国家。

14.Please give me a second chance.
14.请再给我一次机会。

15.He was born at the first Sunday of May.
15.他出生在五月的一个星期天。