在形式上，“the number of ”和“a number of”相差一点点，一个用定冠词 the；另一个用不定冠词 a.可是在语义和用法上，两者的差别就大了。稍微大意，就会犯了谓语动词和真正主语搭配不当的问题。

　　“A number of”的意思是“若干”或“许多”，相当于 some 或 a lot of，和复数名词连用。当它出现在主语前时，谓语动词和主语搭配。必要时，还可以加上形容词great, large, small, good 等。例如：

　　① A number of highly qualified scholars have worked in Singapore.
　　② A great number of junior college graduates opt for business administration courses.
　　③ There are a large number of teaching posts yet to be filled.
　　④ Only a small number of men want to be language teachers.
　　⑤ A good number of books in the market are examination-oriented.

　　“The number of”和“a number of”一样，跟在后头的名词也是复数的，不同的是这里的主语是单数的 the number，不是它后面的复数名词，谓语动词必须和 the number 呼应，如：

　　⑥ The number of undergraduates has increased over the years.
　　⑦ The number of new houses is unable to cope with the ever-growing population.
　　⑧ The number of college graduates in a country reflects its cultural standard.

　　这三个句子里的 the number 的性质和下列主语一样：

　　⑨ The work of lab technicians is dull but important.

　　⑩ The development of a language centre invariably involves long-term planning, adequate human resources, and up-to-date facilities.

　　11. The organisation of large-scale musical concerts calls for much time and energy.

　　写像上面这样句子的人很多，但是由于真正主语和谓语动词隔得太远，一不小心，就出现了动词和主语不呼应的语法错误，如下：

　　12. The number of foreign workers keep on increasing.

　　13. The number of classrooms, offices, and teaching facilities are far from being sufficient.

　　14. The streaming of students in Singapore and Japan differ.

　　15. The cause of student mobs in some countries are related to governments' dictatorship, corruption and ill-treatment of undergraduates.

　　16. The rapid opening up of China's economy in recent years have prompted our businessmen to venture into the Chinese market.

　　12-16里的谓语动词全部要变成单数才对：keeps; is; differs; is related to; has prompted.