首先要搞清楚，是修飾可數名詞或不可數名詞，而不是單數或複數名詞。可數名詞都有複數形式，而不可數名詞沒有複數形式。

a large deal of、a plenty of和a good supply of 在多數情況下修飾不可數名詞，如：a plenty of water, a geat deal of time，不過它們也可以修飾可數名詞，如a plenty of men。

a quantity of在多數情況下修飾可數名詞，如a quantity of boxes, 不過也可修飾不可數名詞，如a quantity of milk。

quantities of與上述的一樣

一、只能修飾可數名詞的詞語有:

many, many a(n), a good / great many, a (great / large) number of, scores of, dozens of等。例如:

Scores of people went there in the first few days after its opening.

開張後的頭幾天,很多人去了那兒。

I have been there dozens of times.

我已去過那兒很多次了。

There’re a number of students reading English in the classroom.

教室裡有許多學生在讀英語。

Many a student has(=many students have)visited the Great Wall.(謂語動詞用單數)

很多學生都遊覽過長城。

In winter, a good many animals sleep under the snow.

冬天很多動物在雪下冬眠。

注意: many所修飾的複數名詞前若有限定詞,many 後面要接of, 表示“……中的很多”。 例如:

A great many(of the) graduates have found jobs.

畢業生中很多人已經找到了工作。

二、只能修飾不可數名詞的詞語有:

much, a great deal of, a great / large amount of等。例如:

Is there much water in the bucket?

桶裡有很多水嗎?

He always has a great amount of work to do.

他總是有很多工作要做。

三、既能修飾可數名詞又能修飾不可數名詞的詞語有:

a lot of, lots of, plenty of (以上三個詞語後謂語動詞的數依of 後的名詞的單複數而定),a great / large quantity of (其後謂語用單數),quantities of (其後謂語用複數)。例如:

There is still lots of snow in the garden.

花園裡還有許多雪。

There is plenty of rain here.

這兒的雨水很多。

A great quantity of flowers was placed in the hall.

大廳裡放了很多鮮花。

There are large quantities of food in the cupboard.

櫥櫃裡有許多食物。

在所有這些表示“很多”的詞語中many, much 是最常用的詞,它們既可以用於肯定句,也可以用於疑問句和否定句。例如:

Are there many people in the street?

街上有很多人嗎?

There isn’t much time left.

剩下的時間不多了。

其它的詞語都用於肯定句,日常會話中常用lots of, a lot of 或plenty of; 正式文體中常用 a great many, a (large) number of, a great deal of, scores of 或 dozens of 等。但若肯定句中有too, so, as, very或how 等詞修飾時,則必須使用 many, much。例如:

The number of the people who lost their homes reached as many as 250,000.

無家可歸的人數多達250,000人。

There is too much work to do.

要做的工作太多了。