二、不定冠词的用法

　　1、不定冠词用来表示“一”这个数量，意思和one差不多：

　　Rome was not built in a day.罗马不是一天建成的。

　　He will be back in a day or two.他将在一至两天内返回。

　　A stitch in time saves nine.及时一针顶十针。

　　这种用法在表示重量、长度、时间等的词组中特别普遍。例如：a pair of socks, a hundred, two yuan a metre, eight hours a day, twice a week, a cup of tea, in a word, one at a time.

　　2、表示人或事物的某一类

　　A steel worker makes steel.

　　A plane is a machine that can fly.

　　A teacher must love his students.

　　A knife is a tool for cutting with.

　　3、表示某一类人或事物中的任何一个。

　　This is an apple.

　　His father is a teacher.

　　This poem was written by a student.

　　She picked up a magazine and began to read.