常考:a university, a uniform, a European, a unit, a one-way street, a one-eyed dinosaur a useful book, a usual day, a united country
an
用于以原音发音开始的单词前
常考: an hour, an honor, an honest student, an honorary degree (荣誉学位)
常见用法
当第一次提起某人或某物时,用a或an起到介绍作用,泛指某一类人或物
例:It′s a book.
指某人或某物，但不具体说明何人或何物
例:A boy is looking for you.
表示数量，有“一”的意思，但数的概念没有one强烈
例:I have a book.
表示“每一”，相当于every
例:once a week
用在序数词前，表示“又一”，“再一”
例:They had a daughter.Then they had a second child-a son.
使物质或抽象名词具体化，表示“一次”，“一种”，“一场”等
例:It's a pleasure to talk to you.与你交谈很愉快。
用于可视为一体的两个名词前
例:a knife and fork
用在某些固定词组中
例:a bit一点儿 a few一些，少数几个,for a while 一会, as a result 结果是, as a consequence, a little, a couple of, many a 许多, in a word总之, have a fever, catch a cold, take a walk, all of a sudden, keep an eye on, in a short while, in a minute, in a hurry, a great many, a pile of books, a pack of dogs, a lot of, a spoon of, a bottle of,as a matter of fact
定冠词 the
定冠词基本用法:特指某（些）人或某（些）物
例:Beijing is the capital of China.北京是中国的首都。
用在普通名词构成的专有名词前
例: the Great Wall长城 the Summer Palace颐和园
指谈话双方都知道的人或事物
例:Open the window,please.
指上文已经提到的人或事物
例:There was a chair.On the chair sat a woman with a baby.The baby was thin.
指世界上独一无二的事物
例:the Changjiang River, the sun,the moon
用在序数词前，形容词最高级前
例:He lives on the fifteenth floor.
You are the youngest in the class.
用在某些形容词前，表示一类人
例:the rich富人 the sick病人 the young年轻人
用在姓氏复数形式前，表示“全家人”或“夫妇俩”
例:The Greens 格林夫妇
一些固定搭配中的定冠词
用在方位名词前
例:in the west,in the east, in front of, on the right/left
某些表示时间的词组前
例: in the moring,in the afternoon, in the end, in the daytime, at the beginning of, at the end of, at the same time,the day before yesterday, in the 1980s, over the past 10 years
习惯用语
例:the same as, by the way, all the same
用在“动词+人+介词+the+人体部位”结构中，而不用物主代词
例:take sb. by the hand抓住某人的手
用在西洋乐器和某些中国乐器前
例:play the piano/guitar/violin/drum
不用冠词
在表示交通工具，学科名称的名词前
by plane,Chinese,American history
在一些固定词组中
go to bed,at home,at once,year after year,in fact
当名词前有this,that,his,any,every,some,no等或有所有格修饰时
She is my sister.
在节日，假日（中国传统节日除外），星期，月份，季节等词前
例:Children′s Day,Monday,Summer,January
在一日三餐，体育类，棋类，颜色，语言等名词前
例:lunch,play basketball/chess,in red,speak English
