a和an的用法口诀:不定冠词a和an, a后辅音an后元，泛指一类或一个，表数语气比one弱,序数词前表又再，most前意非凡，抽象物质动变名，化为具体用法灵，用错a/an被人笑，单名泛指被丢掉，指代物代所有连，位置放错更无颜。

a和an的用法口诀

不定冠词a和an,单数可数名词前;

辅音若在词首发,词前只把a来加;

元音若在词首放,词前an词不敢忘;

不定冠词相当one,但不强调数观念;

不定冠词很关键,四个所指记心间.(每指、泛指、类指和某指)

不定冠词a/an的用法

不定冠词有两个，a 和 an。a用在辅音开头的单词前面;an用于以元音开头的单词前。如：a book, an apple。具体用法如下：

1)表示“一个”、“某一个”、“ 每一”、“再一，又一”、或“同一，相同”等

Eg：

Rome is not built in a day.

A Mr. Smith is waiting for you at the school gate.

He usually works eight hours a day.

You can try it a second time if you fail.

They are of an age./ Birds of a feather flocks together.

2)泛指某一类人或物，意为“任何一个，任一”

Eg:

A square has four sides.

3)当物质名词具体化表示“一(类、阵、份)”等;抽象名词具体化为“……的人或者事”时

Eg:

Green tea is a wonderful tea.

We don’t have much rain here, but last night we had a heavy rain.

Reading is a pleasure for me.

The meeting is a great success.

4)表示季节、月份、日期、三餐的名词，或表示世上独一无二的物体名词前有形容词修饰时

Eg:

We have a every cold winter last year.

This happened on a rain Sunday towards the end of May.

We hope we can see a full moon tonight.

5)源于动词的名词与take/have 连用时

Take a look; take a walk; have a break; have a visit to…