1.英语中不定代词很多，主要有：
1)both, either, neither;
2)all, every, everybody, everyone, everything, each;
3)one, everyone, someone, anyone, no one, none, no, nobody, nothing;
4)some, any, somebody, anybody, something, anything;
5)little, few, much, many;
6)other, another.
它们多数都能作主语、宾语、表语或定语，有些只能作主语、宾语、表语(如somebody)，而every，no只能作定语。作定语时有些英语词典把它们标作限定词(determiner)。
2. both, either和neither：
这几个代词部谈两者的情况：both表示“两者都……”，either表示“两者中随便哪一个(都……)”，neither表示“两者中哪个都不……”。它们可以用作：
1)主语：
Both (of them) are good.
(它们)两个都很好。
Either (of the two books) will do.
(两本书)随便哪一本都可以。
Neither (of the answers) is correct.
(两个回答)哪一个都不对。
2)宾语：
I'll take both (of them) with me.
两个我全带去。
You may take either with you.
(两者)你可以随便带哪个去。
I agree with neither of you.
你们两人的话我都不同意。
3)定语(在这样用时，有的字典标作形容词，有的标作限定词)：
Both (the) seats are taken.
两个座位都有人占了。
You may take either road.
两条路你走哪一条都行。
There are trees on neither side.
两边都没有树。
both还可用作同位语：
You and I are both to blame.
我们两人都有错。
They both agreed to stay.
两人都同意留下。
either...or和neither...nor可起连词作用：
She knew this much be either a whale or a ship.
她知道这不是一条鲸鱼就是一条船。
He had neither wife nor children.
他既没有妻子也没有儿女。
