英语中为了避免重复使用某个或某些词，或者是为了使上下文联系更加紧密，对句中相同的非关键性词语可用替代词（Substitute） 来替代，替代的结果还会使替代词的邻近词语受到强调。归纳起来英语中的“替代”现象主要有四种：
一、名词性替代
用替代词，如one，ones，the same，the kind， the sort等，来替代上文中的名词或名词短语。具体分为：
1.一、二、三人称代词及它们的各种格的形式作替代词，替代上文中的名词及其短语。
If you see Mary, please give her this book. (her 替代 Mary )
Have you received my letter? It was posted a month ago. ( it 替代 my letter)
John and I may move to
Both you and Nancy can go there by bus. You don’t have to walk along with us. (you 替代 you and Nancy )
2.不定代词（+of +N./ Pron.）替代名词短语。常用的不定代词有：
all, both, some, any, enough, several, more, many, much, none, (the) most, (a) few, (a) little, less, (the) least, another, others, the other, either, neither等。
He lent me two books. Both were worth
reading. ( both 替代 two books)
3.one, ones, that, those
a. one 通常用来替代已出现过的可数名词或以可数名词为中心词的名词词组；当one不带任何前置修饰语时，其意义通常是类指的，如：
I lose a good student and you gain one.
If you need a radio，they will provide you with one.
当one 用以替代名词词组中心词时，它通常带有限定词。
Your car isn’t fast enough. Let’s take her new one.
b. ones 是one 的复数形式，只能替代复数可数名词，通常不能单独使用，总是带有限定词或前置修饰语。
I have a new book and several old ones.
He likes yellow roses instead of red ones.
c. that ，those 常用来替代已提到过的事物，以免重复。
The weather of
These machines are better than those we turned out last year.
4.the same, the former, the latter
the same可替代上文中整个名词词组（通常指物）；the former替代前面提到的两者中的前者；the latter替代前面提到的两者中的后者。
A：I’d like beef and fish.
B: I’ll have the same.
Jack and Bill are twins , but the former is taller than the latter.
