A 二者，两者都 the two; the one as well as the other

　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。

 ♣ 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。

 ♣ both, all
　参见all条。
 ♣ 下面两句的意思不同：

　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。

　二者　the two; not only the one but also the other

　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：

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。

　二者，二者都　the two; not only the one but also the other

　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）