代词one, it that的用法在历届高考题中出现的频率较高，是高考的热点之一。笔者结合自己的教学实践在此谈谈它们的一些具体用法，希望能对同学们有一定的帮助。
1．one, it, that常常用来代替或避免重复某个名词。例如：
① I'm looking for a flat. I'd really like one with a garden.
② ---Where did you find your watch? --- I find it in our classroom.
③ The population of China is larger than that of any other country.
2．one可指人或物，只替代单数可数名词，复数用ones. one是泛指，但有限定修饰语，如the, this, that…修饰就变成了特指。如：
① One must do one's duty. ②Mary has a red pencil and Jane has a blue one.
③ The new designs are much better than the old ones.
3．that只指物，不指人，可替代可数名词或不可数名词，具有“特指”性质。指的是同类事物中的另一样东西，即同类异物。如：
The library of our school is bigger than that of yours.(that代替的是另一个图书馆。)
4．One 和that 在代替可数名词时，如果没有前置定语只有后置定语时， the one 和that可互换。但该名词如有前置定语，则只能用the one,而不能用that。例如：
① I will take the seat next to the one(=that)by the window.我就坐窗口的那个座位旁边。
② I prefer the large box to the small one.(one 不可用that替换 )。
5．that的复数形式those代替可数名词的复数。可指人或物，一般后面跟修饰语。如：
① Today's cellphones are smaller than those(=the ones)used in the past.
② The students who do best in exam are not always those(=the ones) with the best brains.
6．the one(ones)或 that ,those 指代某一名词做定语从句的先行词时，其关系代词which在that之后，which不能省略，而在the one、ones 之后,which可省略。如：
① Their problem today is somewhat similar to that which they faced many years ago.
7．代替不可数名词时，应该用that。如：The equipment is different from that.
8．it代替上文所提到的名词时，是指同类事物中的同一样东西，即同类事物。如：
I have lost my pen. I'm looking for it.
9．it和that可代替前面整个句子的意思，而one却不能；that可引导一个限定性定语从句，代替某个先行词（单复数名词均可），it和one则不能；it可代替不定式、动名词或从句，用作形式主语或形式宾语，也可用于强调句型中，而one和that则不能。如：
① ---I will make bed for you. ---It is very kind of you.
② Jim said he had read my novel. But that was not possible.
③ A clock is an instrument that tells time.
④ The students that surf the Internet will be punished by the teacher.
⑤ It is nice to see you again.
⑥ It is no use calling her up.
⑦ I found it impossible for me to pass the test.
⑧ It was I who broke your window.
【巩固练习】
1．---You are learning typing. The computer is very useful.
---I hope to have a computer, but I can't afford to buy .
A. one B. it C. that D. this
2.This computer is so expensive that I cannot afford to buy .Can you bring the price down a little.
A. one B. that C. it D. this
3. ---I'd like a book on English reading.
---Is the book you are looking for?
A. one B. that C. the one D. which
4. ---His car runs much faster than my car.
---That is because the engine in his car works far better than .
A. your one B. yours C. that of yours D. your car's
5. My shoes are the same as you had on the day before yesterday.
A. one B. ones C. that D. the ones
6. I was disappointed with the film, I had expected to be much better.
A. that B. this C. one D. it
7. Mr Li gave the textbooks to all the pupils except who had already taken them.
A. these B. ones C. the ones D. the others
8. I hope there are enough glasses for each guest to have .
A. it B. those C. them D. one
9. I hate when people talk with their mouths full.
A. it B. that C. these D. them
10. ---Why don't we take a little break?
---Didn't we just have ?
A. it B. that C. one D. this
参考答案：
1-5ACCCD 6-10DCDAC
