一、a number of ,the number of

a number of 意思是“许多”，相当于a lot of ; the number of意思是“……的数目,……的数量”，当它作主语时，谓语动词用单数形式。

A number of students like playing computer games.

许多学生喜欢玩电脑游戏。

The number of the students is about 1500 in our school.

我们学校学生的人数大约是1500。

二、基数词变序数词助记歌。

基变序，有规律，末尾加上th;一、二、三特殊记，八加h ，九去e ，ve要用f替;以e结尾变ie，后跟th莫忘记。要想表示几十几，只变个位就可以。

特殊变化：one—first ,two—second ,three—third ,five—fifth ,

nine—ninth ,twelve—twelfth ,forty—fortieth ,

eight-nine—eighty-ninth

三、概数(略数)表达法

数词+hundred/thousand/million/billion+名词复数

hundreds/thousands/millions/billions of+名词复数

例1

1. __people go swimming in summer in Dalian.

A、Thousands B、Thousand of C、Thousands of D、Thousand

2. __the students will take part in this English speech contest.

A. Two hundred of B. Two hundreds of C. Hundreds of D. Hundred of