1.both用作形容词时,作“两个,俩”解,只用作定语,是前位限定词,常与复数名词连用。
2.both用作形容词与定冠词、指示代词、形容词性物主代词、名词所有格等限定词连用时，应置于其前，而不能置于其后。
3.在both之后接名词时用不用定冠词均可。
4.both用作形容词时不用于比较等级。

have it both ways
二者兼得 combine two ways of thinking or behaving; satisfy two demands
You can't have it both ways.You must decide on one thing or the other.二者不可兼得,你必须选择其一。

用作定语
▲～+n.
There are trees on both sides of the street.这条街两侧都是树。
Both these flowers are beautiful.这两朵花都好看。
Both my parents are kind.我的父母都很亲切。
Both (the) students were excellent.这两个学生都很优秀。

both, all
参见all条。
下面两句的意思不同:
Both the foreign guests planted a tree.
两位外宾各种了一棵树。(总共两棵)
The two foreign guests planted a tree.
两位外宾种了一棵树。(只有一棵)

两个孩子都去过希腊。
［误］  The both children have been to Greece.
［正］  Both (the) children have been to Greece.
［析］  形容词both属前位限定词，前面不可以加定冠词，而后面有时则可以。

both作副词时主要和and连用构成关联连词,意思是“…和…都; 又…又…; 既…又…”,连接两个同类型的短语,重点在and之后,用作主语时,谓语动词须用复数形式。

Both the teacher and the students have come.老师和学生都来了。
You've given both your uncle and myself a lot of trouble.你给你叔叔和我带来了许多麻烦。
Mrs. Cox is both kind and gentle to her pupils.考克斯夫人对她的学生又慈祥又和善。
He both speaks and writes Russian.他又能说,又能写俄语。
We should pay attention both to industry and to agriculture.我们都应该重视工业和农业。
Both now and always, I'm your friend.我不但现在,而且永远是你们的朋友。
He can sing and dance both.他唱歌跳舞都行。

品学兼优的学生受人羡慕。
［误］  Both expert and red students are admired.
［正］  The students who are both expert and red are admired.
［析］  both...and...连接两个形容词时,不可用作定语修饰同一个名词,但可用作表语。

［词源］＜中古英语bothe(两)

1.both用作代词时可作主语、宾语和同位语。
2.both作同位语时，一般用在助动词、系词之后,实义动词之前; 但为了强调,both也可置于助动词或系词之前,如一个句子中,既有助动词又有系动词时,可用在助动词后,系动词之前。但是不能紧放在代词前。
3.both与复数名词连用时,若该名词前有the, these或物主代词,其前用both或both of均可,当both跟ｗho或人称代词搭配时只能用both of。
4.both用作代词时,一般不用于否定句,如用否定句也只表示部分否定,不是“都不”而是“不都”。

Both felt that they are very intimate.二人都认为他们亲密无间。
I don't like both of them.他们俩我不是都喜欢。
We both participated in this work.我们俩都参加过这一工作。
And then they both were silent.然后,他们俩都默默不语。
They shall both be put to death.他们俩都将被判死刑。
You are both right.你们俩都对。
John and Mary have both won the prizes.约翰和玛丽都得了奖。
Her brothers, both of whom work in Scotland.她的两个兄弟都在苏格兰工作。
Both of them swim well.他们俩都很会游泳。
Not both the boys were late.〔Both the boys were not late.〕并不是两个孩子都迟到了。

both, either, neither
参见neither条。
下面两句意思不同:
Both of us won a prize.
我们两人各获一个奖品。
We both won a prize.
我们俩共获一个奖品。

1.我写信告诉你们二位我在伦敦的生活。
［误］  I'm writing to tell both about my life in London.
［正］  I'm writing to tell you both about my life in London.
［正］  I'm writing to tell both of you about my life in London.
［析］  both只能指代第三人称,不能指代第一、二人称。
2.他俩很相像。
［误］  They are both alike.
［正］  They are alike.
［析］  代词both不能和alike,as well as,at once,between,equally等连用。