244　a number of和the number of

1　a number of 相当于many，意为“许多”，也可以说a large number of或a small number of （不多），后跟复数名词或代词，谓语动词用复数。a number of 还可表示“若干”。

A number of children are playing on the grass. 许多儿童在草地上玩。

I have a large number of books to read. 我有许多书要读。

Only a small number of students like the film. 仅有一小部分学生喜欢这部电影。

2　the number of 表示“……的数目”，of 后跟复数名词。在这个结构中，the number 是主语，谓语动词要用单数。

The number of students in this class is 40. （正）这个班的学生数是40 。

The number of students in this class are 40.（误）

比较

A number of books are on the desk. 有许多书在桌子上。

The number of books is rising. 书的数量在增加。