英语什么词前面加the,什么前面不加the？

用法举例如下：

一、加the的情况：

1、用在表示海洋、江河、湖泊、山脉、海峡、港湾等的地理名词前。

the Pacific Ocean   太平洋、the Yangtze River   长江 、the Tianshan Mountains   天山山脉

2、用在表示姓氏的复数名词之前，表示一家人或夫妻俩。

The Greens are on holiday now.

格林一家人（夫妇）现在正在度假。

3、用于形容词、分词前，表示一类人或物。 

The injured were taken to the nearest hospital without delay.

受伤的人立刻被送到了最近的医院。

4、用于表示方位的名词前。

the east/south/west/north, the southeast, the right, the left。

Shanghai lies in the east of China.上海位于中国的东部。

Hunan lies on the south of Hubei.湖南在湖北的南边。

5、用在一些固定搭配或习惯表达中，如all the time, at the age of...等。

I’ve kept on thinking about that all the time. 

我一直惦记着那件事。

二、不加the的情况：

1、定冠词不与表示一类人或事物的复数名词连用。

例如: I like reading the books.(×) I like reading books.(√)我喜欢看书。

2、定冠词不能用在某些习惯用语中的名词前面。

例如: I have lunch at the noon.(×) I have lunch at noon.(√)我在中午吃午饭。

3、定冠词不能用在某些专用名词和不可数名词前面。

例如:I like the China.(×) I like China.(√)我喜欢中国。

4、定冠词不能用在节日、日期、月份、季节前面。

例如: Today is the Teachers’ Day. (×) Today is Teachers’ Day.(√)今天是教师节。

5、定冠词不能用在表示称呼语或某些头衔的名词前面(尤其作表语、宾补时)。

例如:Good morning, the sir!(×) Good morning, sir! (√)早上好,先生!

一、加the

1、特指双方都明白的人或物。

2、上文提到过的人或事

3、指世上独一物二的事物

4、单数名词连用表示一类事物,如：the dollar 美元; 
the fox 狐狸；或与形容词或分词连用,表示一类人：the rich 富人; the living 生者.

5、用在序数词和形容词最高级,及形容词only,very,same等前面

6、用在某些由普通名词构成的国家名称、机关团体、阶级、等专有名词前

7、用在表示乐器的名词之前：She plays the piano.她会弹钢琴.

8、 用在姓氏的复数名词之前,表示一家人：the Greens 格林一家人 (或格林夫妇) 

二、

在其余情况下，一般不加the

一、定冠词the的相关语法知识

1、used before nouns to
refer to things or people when a listener or reader knows which particular
things or people are being referred to, especially because they have already
been mentioned or because what is happening makes it clear （用于名词前，指听者或读者已知的事物或人，尤指已提到的或能被领会的事物或人）

•I just bought
a new shirt and some new shoes. The shirt was quite
expensive, but the shoes
weren't.我刚买了一件新衬衣和几双新鞋；衬衣很贵，但鞋子不贵。

2、used before some nouns
that refer to place when you want to mention that type of place, without showing
exactly which example of the place you mean （用于某些名词前，表示泛指一类地方） 

3、used before
superlatives and other words, such as 'first' or 'only' or numbers showing
something's position in a list, which refer to only one thing or person
（用于形容词或副词最高级及表示排名的词前） 

4、used before numbers that refer to periods of ten years （用在逢10的数字前）

•the sixties60年代

5、used before each of two comparative adjectives or adverbs when you want to show
how one amount gets bigger or smaller in relation to the other
（用在两个形容词或副词比较级前，表示“越…越…”）

•The sooner I get
this piece of work finished, the sooner I can go
home.我越快完成这项工作，就能越早回家。

6、used instead of a
possessive adjective such as your, her or my （用于代替 your，her，my 等词）

•He held his
daughter by the arm.他抓着女儿的胳膊。

•I can't
remember where I parked the (= my)
car.我不记得把车停在哪里了。