下面三句中的斜体部分不能互换：
Who invented the radio? （指类别）
Who had a radio? （指同类中的任何一个）
Who manufactured radios?（指这一类中的所有个体）
man 指“人类”时，不用the。例如：
Man will conquer nature.
b) 用于指世上独一无二的东西，如 the moon，the sun，the world等。
c) 用于表示“乐器”的名词前，但一般不用于表示“体育运动”的名词前。例如：
Can you play the guitar?
I play football every day.
d) 用于某些形容词前，可表示“一类人”。例如：
The young are impatient；they want changes.
e) 一般不用于表示“疾病”的名词前。例如：
I’m just recovering from rheumatism（风湿病）.
下列病名前一般用a／an：
I have an ache in my head (a pain in the neck).
He has a cold／a fever.
特指时需要用the。例如：
Jim has never really got over the malaria（疟疾）he caught in the East.
f) 一般不用于表示“膳食”的名词前，但有形容词修饰时用the。例如：
Breakfast is served at eight.
The wedding breakfast was held in her father’s house.
 如果泛指，用a／an。例如：
He gave us a good breakfast.
g) bed, church, college, court, hospital, market, prison, school, sea和work等名词用来指有关活动时，一般不用冠词。例如：
It’s time for children to go to bed. （指to sleep）
He goes to church every Sunday. （指to pray）
After the crash，seven people were taken to hospital. （指to be cured）
He spent six months in prison. （指to be punished）
After I leave school, I want to go to (a) university. （指to study）
Ken is a seaman. He spends most of his life at sea. （指to sail）
注：在美国英语中，通常用a／the hospital，a university。
出于其他目的，如去参观、访问这些地方或谈到这些地方时，根据情况用 a 或 the。
例如：
There is a bed in the room.
She was putting clean sheets on the bed.
The workmen went to the church to repair the roof.
Tom went to the prison to visit his brother.
I would love to live near the sea.
home 单独使用时，无冠词；有修饰语时，用 the 或 a。例如：
She left home.
We went to the bride`s home.
I don’t have a home to go to in this city.