2. 定冠词用法
(1) 特指某（些）人或某（些）事物。例如：
The book on the desk is an English dictionary.
Beijing is the capital of China .
(2) 指说话人和听话人都熟悉的人或事物。例如：
Open the door, please.
Jack is in the library.
(3) 上文提到过的人或事物。例如：
Yesterday John's father bought him a new bike. The bike cost him 200 yuan.
(4) 表示世界上独一无二的事物。例如：
The sun rises in the east and sets in the west.
(5) 用在序数词和形容词最高级之前。例如：
Shanghai is the biggest city in China .
January is the first month of the year.
(6) 用在某些形容词之前，表示某一类人或事物。例如：
The nurse is kind to the sick.
We should take good care of the old.
(7) 用在某些专有名词之前和某些习惯用语中。例如：
the Great Wall, the Summer palace, in the morning, in the open air 等。
(8) 用在姓氏复数之前，表示 “ 某某一家人 ” ， “ 某某夫妇 ” 。例如：
the Browns, the whites 等。

3. 不用冠词的情况
(1) 某些专有名词，抽象名词和物质名词前一般不用冠词。例如：
China, Canada, Japanese, glass, water, love 等。
(2) 名词前已有作定语用的 this, that, my, your, whose, some, any, no, each, every 等代词时，不用冠词。例如：
That is my cap.
I have some questions.
Go down this street.
(3) 复数名词表示一类人或事物时，不用冠词。
They are workers.
We are students.
(4) 称呼语前不用冠词，表示头衔和职务的名词前也不加冠词。例如：
I don't feel well today, Mother.
Bush was made president of the U.S.
(5) 三餐饭的名称前，球类活动，学科和节目名词前，常不用冠词。例如：
I have lunch at home.
He often plays football after class.
We have English and maths every day.
(6) 在某些固定词组里，名词之前常不用冠词。例如：
By air, at night, at home, go to bed, go to school, on foot, from morning till night 等。