4.其他用法

(1)在“of/at”后面出现，以表示“同一类”这个概念。

It refers to advertisement messages that are sent via e-mail to thousands of customers at a time．(人教大纲版高三第183页)

它(垃圾邮件)指的是通过电子邮件同时发给成千上万个用户的广告邮件。

Things of a kind come together，so do people of a mind．

物以类聚，人以群分。

Your shoes and mine are of a size．

你的鞋和我的尺码一样。

John and Jack are of an age．

约翰和杰克同庚。

(2)常在rather，quite，many，half，what，such等词后面出现，形成固定用法。

Tom is rather a fool．

汤姆相当傻。

I think Chinese is quite a useful language．

我觉得汉语是极其有用的语言。

Many a student has asked that question．

很多学生都问过那个问题。

The visitor left half an hour ago．

来访者是半小时前离开的。

How can you say such a thing?

你怎么能这样说呢?

提示：

①如果名词前有其他形容词修饰的话，a也可以置于quite和rather之前。

As it happens，there is a rather nice place for sale，not too far from London．(BNC)

=As it happens，there is rather a nice place for sale，not too far from London．

恰好在离伦敦不远的地方有一个绝好的可以作销售的地点。

Santa Maria is a quite beautiful church．(BNC)

=Santa Maria is quite a beautiful church．

圣玛丽亚是个极其漂亮的教堂。

②half a/an hour=a half hour

(3)a用在“so/as/too/how/however/that+形容词”之后。

We have not had so hot a day before．

我们以前没有经历过这么热的天。

Susan is as clever a girl as Anna．

苏姗和安娜一样聪明。

That is too difficult a book for beginners．

这本书对于初学者来说太难了。

No one knew how serious a problem it was until later．

人们后来才知道问题的严重性。

However difficult a job it may be，we'll try our best．

无论多么难，我们都将竭力把这个事做好。

(4)a用在“形容词比较级(+形容词)”之后。

He is no less great a genius．

他真是一个旷世奇才。

The fact was that there had been perhaps no greater mystery among nations，no more confused an epic，than the story of Red China．(Red Star Over China，Edgar Snow)

事实是，在世界各国中，恐怕没有比红色中国更大的谜、更混乱的传说了。

He might have asked the question in more serious a tone．

他本可能用一种更严肃的语气问这个问题的。

(5)用在不可数名词前，表示一种特殊含义。

①用在一些表示动作的名词(rest，walk，look，try，sleep，breath等)前，意为“一次”、“一下”、“一会儿”等。

Let's have a rest．

我们休息一会儿吧!

He made a second try．

他又试了一次。

After looking round，he decided to have a look upstairs．

环顾了一下以后，他决定往楼上看看。

②表示“一种”、“一类”。

“You don't understand，”said Joe，a cruel light shining in his eyes．

“你不懂，”乔说，眼睛里闪着(一种)凶狠的光。

③表示风、雨等的“一阵”。

An hour later，he was woken up by a violent knocking on his door．

一个小时后，他被一阵急促的敲门声弄醒了。

That's why we are most likely to see worms after a heavy rain．

这就是我们常常在大雨后看到这种害虫的原因。

④表示“某种程度”。

China has a population of over one billion．

中国有十多亿人口。

A French man had caught a very bad cold．

一个法国人得了重感冒。

He seemed to be in a fever．

他似乎在发高烧。

⑤表示饮料的“一份”、“一种”。

Mao-tai is a famous Chinese wine．

茅台是一种很有名的中国酒。

I want a black coffee．

我要一份清咖啡。

Give me a soup．

给我一份汤。

⑥放在形容词最高级之前，这时最高级表示“非常”的意思。

This is a most troublesome case．(人教大纲版高二下第67页)

这是一件非常棘手的案子。

⑦出现在许多惯用语中。如a little，a lot，a bit，a good(great)many，many a，a great number of，as a rule，in a hurry，all of a sudden，take an interest in，take a pride in，make a fool of，have a cold，have a headache等。

提示：

catch a cold中的a可用也可省略。牙疼和耳朵疼前面没有冠词，只能说have toothache，have earache。