2. both, either和neither用于两个人或事物。both总用作复数，either和neither总用作单数，如：
　　　Both are right.
　　　Neither of the answers is correct.

　　3.all,every,each：each指两个或两个以上，all和every指三个或三个以上，all强调总和、整体。each和every都表示"每个"，只是each强调同类事物的个别性，every强调同类事物的共同性。each只能代替可数名词，all可代替可数和不可数名词，every用在单数可数名词前表示"每一个"，用在不可数抽象名词前表示"完全的"、"充分的"，如：
　　　All work and no play makes Jack a dull boy.
　　　There is a line of trees on each side of the street.
　　　I have every reason to believe that she is a fine girl.

　　4. one指人时，表示"一种人"或泛指人，它还用来代替前面出现过的名词，避免重复，如：
　　　He is not one to accept failure easily.
　　　I have not got a tape recorder. I'll buy one tomorrow.

　　5. other和another：other表示"另外、其余"，the other指两个中的一个，the others指已提到的其余部分，another表示"又一个"、"再来一个"，只代替可数的单数名词，但也可修饰复数名词，表示"另外的"、"附加的"，如：
　　　She has two sons. One is a doctor, the other is a worker.
　　　I don't like the color of this bag. Will you please show me another?
　　　I gave him another ten dollars.

　　6. (a) little, (a) few, many, much都是表示数量的不定代词。many, (a) few只用于复数可数名词，much, (a) little只用于不可数名词，如：
　　　Many people are called, but few are chosen.
　　　You invested so much money in your business, but profited so little from it.

　　7. some和any是表示不定数量的代词，可修饰可数或不可数名词。some多用于肯定句，any多用于疑问句、否定句或条件从句中，如：
　　　There are some tables in that room.
　　　We haven't had any rain for months.

　　some也可用于疑问句中表示请求、建议、反问等，any意为no matter which（无论哪一个）时，也常用于肯定句，如：　
　　　Would you mind buying some stamps for me?
　　　Anyone will do.

　　8. some, any, every和no可与one, body, thing构成合成代词。这些代词都作单数看待，如：
　　　There is somebody on the telephone for you.
　　　Nothing ever pleases her.