1. 用some还是用any
1) 一般说来，some用于肯定;any用于否定，例如：
There are some letters for you. There aren't any letters for me.
2) 疑问句中，一般用any，如问话人心中已经有“数”，或认为对方会做出肯定回答时，用some。试比较：
Have you any apples? (I can't see any.)
Could I have some of those apples? (which I can see.)
3) 注意其它方式的否定因素也可决定应该用any，如：
I don't think there are any letters.(主句动词否定转移，从句中用any。)
The boy solved the problem without any difficulty. (介词without含否定意味。)
4) any在表示“任何(人或物)”时，可用于肯定句中：
Oh! Any book will do;I just want something to read on the train.
5) 当说话人心中有“数”(尽管可能不是具体数字)时，否定句中也用some，如：
Some boys haven't done their homework.(肯定有人没做，尽管不一定知道是多少人。)
6) any可用条件从句中，表示情况不明或未定，如：
Let me know if you need any help.(不知道对方是否需要帮助。)
试比较： Let me know if you need some help.(知道能如何提供帮助。)
2. all和both
1) all和both后面的of可有可无。
All / Both (of) the desks are new.
注：Both the desks... = Both of the desks... = Both desks...(the或of the可有可无)
2) 注意下列两种句子里all/both的位置：
They all / both agree with me. I agree with them all / both.
句中all或both直接跟在代词(主格或宾格)之后作同位语;其它不定代词不能这样用。
3) all/both同频度副词一样，可位于句中(主、谓语之间或谓语动词结构之中)，如：
They all / both came. They were all / both waiting.
(注;each也能这样用，其它不定代词都不能。)
3. either与neither
either指“两者之中任何一个”，neither指“两者都不”通常与单数动词连用。但在非正式英语中也可与复数动词连用。例如：
You've got two answers. Either is correct. Neither is wrong.
There are trees on either/each side of the street.
Neither of the books is worth reading.(=Neither of the books are worth reading)
4. nobody, no one, nothing和none
nobody和no one指人，作单数，后面不能接of 短语,例如：
Nobody/No one knows why she was late again.
Nobody was hurt in the match，were they?(反意疑问句中，可用复数代词they来代替。)
nothing指物，作单数;none指人或物，作单救或复数均可。none既可用于可数名词，也可用于不可数名词, 例如：
None of the money on the table is mine.
None of his reasons was/were true.
There's nothing on the table but a blue cap.
Of all my classmates， none likes dancing.
5. every与each
every强调的是“全体”;each则强调的是具体“每一个”。例如：
On every/each side of the square there were soldiers.
(The square has more than two sides。every side = each side =all sides表示“每边、各边”。) 试比较：
On either/each side of the road there were soldiers.
(The road has only two sides. either side= each side = both sides，表示二者之中“每一边”。)
此外，each可作名词性代词，如：
Each has two books.(each作主语)
We each are satisfied with our own rooms.
(each作同位语，常位于主语和谓语动词之间，谓语动词及代词等应与主语一致。)
We are satisfied with our own rooms each. (each作同位语时，也可置于句末。)
6. other, the other和another
1) other表示“另外的(人或物)”，“其他的(人或物)”，其复数形式为others。例如：
There are other ways of doing this exercise.
Lei Feng was always ready to he1p others.
2) the other表示两者之中的“另一个(人或物)”，其复数形式为the others，例如：
He has a pen in one hand and a book in the other.。
Only three of the students were in the classroom;the others were all on the playground.
当other泛指“别人”时，前面不加定冠词：
We must always be ready to help others.
3) another表示不定数目中的“另一个或类似的下个(人或物)”，还可与数词连用，表示“再，又”的意思。例如：
How about another cup of tea?
The strike may last another two weeks.
7. one
1) one只可用于指代可数名词，其复数形式是ones。例如：
If you can't find your pen，use the one on the table.
What nice shirts!which one/ones shall we buy?
2) one/ones通常不能直接用在their，my，his等物主代词以及a(n)，own，several和名词所有格后面。例如：
His knife seems sharper than mine.(不能用 my one代替mine)
They don't like this town;they want very much to go back to their own.(不能用 * their own one代替their own 或 their own country)
但是，当one/ones前面还带有形容词时，则例外。如：
Have you any knives?I need a sharp one.
My old dictionary isn't as good as John's new one.
3) the/this/that one与that：
that可以指代不可数名词，而one不能。如：
The weather in Wuhan is much warmer than that in Tianjing. (that不能用the one取代) that后面常接of短语，例如：
This dictionary is more expensive than that one.(that one=that dictionary. one一般不省略)
The window of your room is much bigger than that of mine.(that=the window，它后面有of短语，一般不用the one替代)
有时候the one和that可以互相取代，如：
The gold ring is in that box --- the one(=that)with the key in the lock.
4) one可以泛指人，相当于you，we，people，其所有格为one's。例如：
One should do one's/his duty.
