辅音字母开头：a tree, a university, a house, a European country, a one-eyed man 元音或半元音开头：an apple, an umbrella, an hour, an elephant, an opera
1．如果不定冠词后面第一个词以元音字母u开头就用a。例如university, useless, useful, unit, uniform。
3．如果不定冠词和名词前有其他词，不定冠词的形式仍取决于它后面第一个词的语音形式。例如an actress, a beautiful actress。
dictionary is useful book.
underground train can start and stop quickly.
This is book.
He used to be engineer.
boy is waiting for me.
Give me pen, please.
Behind the house there is garden.
few, little, lot of, number of, just minute, in hurry, for while, for long time, cup of, bottle of, have rest, have talk, have fever, have good time, have(take) walk, have toothache, take bath, give lesson
in the 1980s 20世纪80年代
in the nineteenth century 二十世纪
girl in red is my sister.
man over there is our English teacher.
book on the desk is mine.
Here is a picture of a modern car factory. My father works in factory.
The Nile is longest river in the world.
He won first prize.
The sun rises in east.
rich, sick, new , false
People’s Republic of China
the United Nations
North China Plain
The sun rises in the east, and sets in the west. 太阳从东边升起，从西边落下 Jiangxi lies in the south of China. 江西位于中国的南方。
in the morning(/afternoon/evening), in the day, by the way, on the whole, the next morning, all the year around, the other day, at the same time
He often plays the piano at five in the afternoon. 他常在下午五点弹钢琴。
Can you play the violin? 你会拉小提琴吗？
China, Beihai Park
The letter is from my father.
I have a book in my hand.
Horses are useful animals.
I like cakes.
Today is Sunday.
Spring is the best season in the year.
go to school , be in hospital, be in prison
I like to play basketball.
We have lunch at school.
（1）在school, college, university, hospital, prison, church, class, table, bed等表示机构名称、组织名称和家具的名词前，用定冠词和用不定冠词意义有差异。用定冠词强调处所，而不用定冠词意义有所引申。比较：
at table 就餐
at the table 坐在桌边
go to school 去上学
go to the school 去这个学校
in hospital 住院
in the hospital 在这家医院
go to prison （违法而）进监狱
go to the prison 到监狱
go to church 做礼拜
go to the church 到教堂
in class 在课堂上
in the class 在班级里
a little/few 有一点
a number of 许多
the number of ??的数目
in front of 在??前面
in the front of 在??前部
take place 发生
take the place of 代替
out of the question 根本不可能
out of question 没有问题
the most beautiful 最漂亮
most beautiful 非常漂亮
for a moment 片刻
for the moment 暂时
1 There is “h” in “photo”．
A． a，a B． an，the C． the，an D． an，an
2 She is honest girl．
A． an B． a C． / D． the
3 He goes to school after ．
A． / B． the C． an D． a
4 —Does Jim have _______ ruler？
—Yes，he has _______ ．
A．an；some B．a；one C．a；／ D．any；one
5 This is ____ interesting book and it is also ____ useful one.
A. an; an B. an; the C. an; a D. a; a
6 A computer is ____useful tool in ____ world today.
A. an; the B. a; the C. the; the D. a; a
7 Now he is ___ artist. 1 have known him since he was ___ one-year-old boy.
A. a; an B. a; a C. an; an D. an; a
8 There is____ bridge over there. ____ bridge is made of wood.
A. the; The B. a; A C. the; A D. a; The
9 She saw____ English film last Sunday. But she can not remember ____ name of ___ film.
A. an; a; a B. a; the; a C. an; the; a D. an; the; the
10 He takes a bath in____evening.
A. the B. / C. a