a number of

a number of
一些，许多
A number of questions came up at the meeting.
会议上提出了许多问题。
A number of cables are needed in this project.
这项工程需要大量电缆。
I have consulted a number of law books in the British Museums.
我查阅了大英博物馆里许多法律书籍。
Quite a number of world famous paintings are on show in this exhibition.
有许多的世界名画在本次展览会上展出。

详解：

英语中有很多短语表示“大量；许多”，根据性质可分为以下三类：
★ 修饰可数名词的有：a good / great many, a large / great number of, scores of等，谓语动词用复数形式。如：
A great / good many words and expressions have come into the language from American English.
这门语言吸收了美国英语中的许多单词和短语。
There were scores of boxes, all waiting to be checked and loaded. 大批的箱子等着检验后装运。
★ 修饰不可数名词的有：a large amount of等，谓语动词用单数形式。如：
He has spent a large amount of money on his new house.
他在新房子上花费了许多钱。
★ 既能修饰可数名词，又能修饰不可数名词的有：a lot of, lots of, plenty of等，谓语动词根据被修饰的名词是可数还是不可数来决定单复数形式。如：
There are a lot of / lots of people in that room.
那个房间里有许多人。
There’s a lot of / lots of rice in the bag.
那只口袋里有许多大米。
There are plenty of eggs in the fridge.

a lot of<-->a pair of