什么时候the和a,an都可以用?

什么时候the和a,an都可以用?

冠词
冠词是用在名词前面,帮助说明名词所指的人或事物,是泛指还是特指的词.冠词是一种虚词.
冠词分不定冠词（The Indefinite Article）和定冠词（The Definite Article）a, an是不定冠词,the是定冠词.
an, a是不定冠词,仅用在单数可数名词前面,表示“一”的意义,但不强调数目观念.a用在以辅音（指辅音音素）开头的词前, an用在以元音（指元素音素）开头的词前,如：
a boy an hour
a history class an island
a university an elephant
a hero an old man
不定冠词的用法：
1. 表示人或事物的某一类
A steel worker makes steel.
A plane is a machine that can fly.
2. 表示某一类人或事物中的任何一个.
This is an apple.
His father is a teacher.
3. 泛指某人或某物,但不具体说明何人何物.
A comrade is waiting for you downstairs.
I met an old man on my way to school.
4. 表示“一个”的意思
He will be back in a day or two.
He tried to send a picture of a face.
5. 有时也表示“每”的意思
We have three meals a day.
我们一日三岁.
He walks ten miles an hour.
他一小时走10英里.
We have six classes a day.
我们一天上六节课.
He drives the car at thirty miles an hour.
如果把不定冠词后的名词变为复数,只把不定冠词去掉还不行,还得补上一个数词或不定代词（some, any）
The plan will be ready in a few days.
这是因为“一个”或“某个”变为复数时,就成为“几个”或“某几个”的缘故.
定冠词的用法：
定冠词the具有确定的意思,用以特指人或事物,表示名词所指的人或事物是同类中的特定的一个,以别于同类中其他的人或事物,相当于汉语中的“那个”或“这个”的意思.它可以和单、复数名词,也可以和不可数的名词连用.用在以辅音音素开头的词前读[ð? ],用在以元音音素开头的词前读[ði ] ,在特别强调时读[ði:].
II定冠词的基本用法：
1. 特指某（些）人或某（些）事物.
Give me the book.
Did you hear the talk given by Mr Li?
How do you like the film.
Have you got the letter?
2. 指谈话双方都知道的人或事物.
Where is the teacher?
Open the door.
3. 复述上文提过的人或事物.
I have a beautiful wallet, but the wallet was stolen yesterday.
4. 世界上独一无二的事物等（月亮、地球、天空、宇宙）
The sun rises in the east.
The earth goes round the sun.
the globe, the universe.
the atmosphere大气层
5. 用在方位名词前
in the south, in the west ,in the north
6. 用在序数词或形容词最高级前
The first thing I want to say is to listen carefully in class.
He is the tallest one in our class.
7、表示两者间“较……的一个”时用定冠词
The older of the two noblemen took a light.
He is the taller of the two boys.
8. 用在单数可数可数名词前表示一类人或事物.
The horse is a useful animal.
9. 定冠词用在形容词前,表示一类人或东西.
The rich, the poor ,the wounded ,the deaf
10. 冠词可用在党派、阶级、民族名词前
The Chinese people中华民族
The working class 工人阶级
The Communist Party
11、用在姓氏的复数形式前表示一家人,或这一姓的夫妇二人.
The Lius live upstairs.
The Johns are watching TV.
12、在乐器前加the
the piano the violin
13、在习惯性短语中
in the morning in the afternoon
14、在人或物后有限定性的后置定语
The man standing by the gate is Li Feng.
15、代替所有格代词,表示人体的一部分
He received a blow on the head
他头上挨了一击.
John’s brother took him by the hand.
约翰的哥哥牵着他的手.
16、在世纪,年代名词前用冠词.
In the 1980s或in the 1980’s 20世纪80年代
in the nineteenth century 二十世纪
17、专有名词前冠词的用法.
1. 在江河、山脉、湖泊、海洋、群岛、海峡、海湾运河前用the.
the Changjang River 长江
the Hudson River 哈得孙河
the West Lake 西湖
the Pacific Ocean 太平洋
the Yellow Sea 黄海
the Suez Canal 苏伊士运河
the English Channel 英吉利海峡
the Persian Gulf 波斯湾
the British Isles 布列颠群岛
2. 在含有普通名词构成的专有名词前用the.
the Great Wall 长城
the Summer Palace 颐和园
the United States 美国
the October Revolution 十月革命
the Chinese People’s Liberation Army 中国人民解放军
the Long March 长征
3. 在某些建筑物前
the Great Hall of the People 人民大会堂
the Museum of Chinese History 历史博物馆
4. 在某些组织机构前
the United Nations 联合国
the Department of Education 教育部
⑤节日名：New Year’s Day 新年,元旦
Women’s Day 妇女节
Labour Day 劳动节
Children’s Day儿童节
April Fools’ Day愚人节
National Day国庆节
Thanksgiving Day感恩节
Christmas Day圣诞节
但我国的节日前用定冠词
the Spring Festival春节
the Mid-Autumn Festival中秋节
但也有一些专有名词前不加冠词
1. 街名：Wang Fu Jing Street王府井大街
Naking Road南京路
2. 广场名：Tian An Men Square天安门广场
3. 公园名：Pei Hai Park北海公园
Hyde Park海德公园
4. 大学名：Beijing University北京大学
Zhejiang University浙江大学
但也可说the University of Beijing the University of Zhejiang
什么时候不用冠词
1. 在物质名词,抽象名词前不用冠词
The desk is made of wood.
What is work? Work is struggle.
2. 专有名词前不加冠词
Canada, Beijing ,Lei Feng
3. 名词前有物主代词指示代词,不定代词,名词所有格修饰时
this, my,that, those, these, her
4、月份,星期,季节前不用冠词
Sunday March summer winter
5、在表示一类人或事物的复数名词前不用冠词
Horses are useful animals.
My mother and father are school teachers.
6、当一个名词用作表语,冈位语补足语来表示某人在当时或现刻的职位或头衔时,前面不用冠词.
He is chairman of the Students’ Union. 他是学生会主席.
They elected him president of the U.S. 他们选他当美国总统.
这里指的职位大体是指独一的职位,“主席”、“主任”都只有一个,如不是独一的要加不定冠词.
She is a teacher of English in our school. 她是我校的一位英语教师
7、在三餐前不用冠词.
breakfast, lunch, supper 如这些词前有形容词修饰可用不定冠词.
I had a good lunch yesterday.
I have breakfast at 7 every day.
8、在球类,棋类名词前不用冠词.
Play football (basketball, Volleyball) chess
※抽象名词,物质名词前不用冠词,但后有定语修饰加the.
He is fond of music.
The music of the film is very beautiful.
Science is making rapid progress in China.
科学正在中国飞速发展.
Physics is the science of matter and energe.
物理学是物质和能量的科学.