5.用于形容词和分词前表示一类人

the reach, the living, the wounded

4.用于演奏乐器

play the violin, play the guitar

3.表示说话双方都了解的或上文提到过的人或事

Would you mind opening the door?

2.用于世上独一无二的事物名词前

the universe, the moon, the Pacific Ocean

1.表示某一类人或物

In many places in China, ___ bicycle is still ___ popular means of transportation.

A. a; the　　　　 B. /; a　　　 C. the; a　　　 D. the; the

10.与序数词连用，表示“又一，再一”。

In order to find a better job, he decided to study a second foreign language.

为了找到一个更好的工作，他决定再学习另外一门外语。

9.用于抽象名词具体化的名词前

success(抽象名词)→a success(具体化) 成功的人或事

a failure 失败的人或事　　　 a shame　 带来耻辱的人或事

a pity　 可惜或遗憾的事　　　 a must 必需必备的东西

a good knowledge of 精通掌握某一方面的知识

8.用于so(as, too, how)+形容词之后

She is as clever a girl as you can wish to meet.

7.用于quite, rather, many, half, what, such之后

This room is rather a big one.

6.用于固定词组中

a couple of, a bit, once upon a time, in a hurry, have a walk, many a time