英语的代替现象比汉语普遍，使用代词的场合比汉语多。大多数句子中均用代词代替上文谈到的人、事物或情况，避免了对较多名词、冠词的反复使用，这样大大简化了句子。
最常用于表示替代关系的词语有it, that, which, one, so等，近几年高考试题中均对这些词的用法进行了考查，可见这几个替代词的用法非常重要。下面归纳它们表示替代时的不同用法。
一、it的用法
1、it指代上文所提事物的本身（it表时间、强调等的用法此处不阐明），如果所代替的事物为复数，则应该用they或them表示。
2、it也可以用来代替上文所提到的一件事。
1.The Parkers bought a new house but _____ will need a lot of work before they can move in. (NMET2001,25)
A.they B.it C.one D.which
2.I am looking for a house. I’d like ____ with a brook around_____.
A.one,it B.it,it C.one,one D.it,one
3.Mary’s mother always told her to work hard, but______didn’t help.
A.one B.he C.she D.it
4. —Do you like these photos? — Yes, ____are very beautiful and I like____ very much.
A.they,those B.they,them C.ones,ones D.the ones, the ones
5.—Are you still using your old car? --No, I sold___the other day.
A.it B.one C.that one D.the one
6.Yesterday I lost my pen, but now I have found_____.
A.it B.them C.ones D.those
7.—Where are my books? --_____ are on the TV set.
A.Ones B.Those C.The ones D.They
8.Where have you put my shoes? I can’t find_____anywhere.
A.them B.those C.ones D.the ones
9.Where did you buy the watch? Would you please get____ for me?
A.it B.one C.the one D.them
10.Don’t read in the sun. ____ is bad for your eyes.
A.One B.The one C.It D.This
二、that的用法
1、that用来指前文中确定的非同一事物，常用来替代与定冠词或形容词性物主代词连用的单数可数名词或不可数名词，相当于“the+名词”，其复数形式为those。
2、that表替代时为始终是特指（作指示代词和关系代词用时另论），可指上文谈到的人、物或情况（均为单数），可代替可数名词和不可数名词。
3、若that所代替的内容为前置用法，即要代替的内容将出现在下文中，一般用this,these或the following表示。
1.—He was nearly drowned once
—When was_______?(NMET2002 Beijing spring)
—_____was in 1998 when he was in middle school.
A.that,It B.this,This C.this,It D.that,This
2.Equipped with modern facilities, today’s libraries differ from______ (2003 Shanghai spring,26)
A.those of the past B.the past C.which of the past D.those past
3.Few pleasure can equal __of a cool drink on a hot day. (NMET99,17; NMET99 Guangdong,29)
A.some B,any C.that D.those
4.The population of Sichuan Province is larger than ____of any province in China.
A.one B.it C.that D.the one
5.What I want to suggest is_____: Everyone should have another try. We needn’t only wait for help.
A.that B.this C.it D.one
6.You see, the accident happened like_____: The red car hit the bus and made all the traffic stop.
A.that B.this C.it D.one
7.Listen! ________ is about the lessons we will have to finish today.
A.It B.The one C.The following D.One
8.The climate here is quite different from____ of Shengyang.
A.that B.it C.one D.the one
9.The study of idioms is as important as____ of grammar.
A.one B.that B.it D.this
10.My seat is next to_____ of my teacher.
A.that B.it C.this D.one
三、which的用法
1、在后置的非限制性定语从句中代替上文出现的事物或情况（单数或复数）。
2、在问句中作为疑问代词，在名词从句中作为连接代词用，其含义为“哪个、哪些”。
3、如果非限制性定语从句的先行词不是指主句内容，而是指具体的人、时间、地点，则不用which。
4、如果非限制性定语从句前置，则用as。
1.Dorothy was always speaking highly of her role in the play, _____, of course, made the others unhappy. (NMET2000,17)
A.who B.which C.this D.what
2.The result of the experiment was very good, which we hadn’t expected. (NMET2000 Beijing spring,10)
A.when B.that C.which D.what
3.China has its own English language newspaper, China Daily,______is published in Beijing.
A.that B.it C.which D.one
4.China Daily has plenty of advertisements, _____ help to cut the costs of making the newspapers.
A.that B.it C.which D.they
5._____ would you like better, the blue one or the red one?
A.Which B.What C.That D.How
6.I don’t know in_____ direction the thief ran away.
A.whose B.what C.which D.where
7.The old scientist went to the U.S.A in 1921, _____ he spent his last years.
A.which B.when C.where D.that
8.____we all know, China is developing at a great speed to catch up with the western countries.
A.Which B.That C.It D.As
9.At last we came to an old castle, _____ roof was in a bad state.
A.which B.what C.whose D.that
10.The man was standing behind the window, _____ he could see what was happening outside the house.
A.from which B.from where C.where D.which
四、one 的用法
1、 常用来代替与上文所提到人或物相类似的不确定的另一人或物（泛指），且被替代者为可数名词单数形式。
2、 若下文替代者表示非特指含义，则用a/an—adj—one形式表示；若下文替代者为另一特指含义，则用the one或the—adj—one表示；若下文替代时为复数含义，则用the—adj—ones 或the ones表示。
3、 one作替代词用时，其前可加某些形容词或限定词，如the,this,that,which,each,
every,any， 但一般不能直接在其前加物主代词。
4、one被后置定语修饰表示特指时，前面应加the；被形容词修饰表示泛指时，其前应加a/an；被形容词修饰表示特指时其前应加the。
5、one作主语时，其对应的物主代词用 one’s或 his，反身代词用 oneself或 himself，重复主语用 one 或he。
1.I hope there are enough glasses for each guest to have_______ . (NMET95,21)
A.it B.those C.them D.one
2.—Why don’t we take a little break? —Didn’t we just have________? (NMET2000,23)
A.it B.that C.one D.this
3.Meeting my uncle after all these years was an unforgettable moment, one I will always treasure. (NMET2002,35)
A.that B.one C.it D.what
4. —Did a letter come for me? —Yes, there was _______for you this morning.
A.one B.it C.the one D.that
5.He has a blue pen and two red ______.
A.one B.ones C.those D.the ones
6.I brought a necklace to you that day, but it was________.
A. a different one B.different one C.the different one D.different ones
7.I don’t like this blue cat, I’d like______.
A. the red one B.red one C.a red D.that red
8.I don’t like this expensive cake, _______ is OK.
A.cheap one B.that cheap C.a cheap one D.a cheap
9.____should love____country.
A.One,her B.She,her B.One,one’s D.One,ones
10.Such a drug will make_____ find it hard to go without it.
A.it B.that C.one D.ones
11.Yesterday I lost my pen, but I’ve bought______.
A.it B.that C.one D.the one
12.Young people like seeing the film, but old_____ don’t.
A.those B.ones C.one D.them
13.This book is_____that is needed by all of us.
A.it B.one C.that D.the one
14.He is_____who gave us the talk yesterday.
A.that B.one C.the one D.himself
15.Is this museum_____they paid a visit to yesterday?
A.that B.where C.the one D.which
16.Your old bike is_____, it’s much better than_____
A.a good one,my new one B.good one,my one
C.a good,my new one D.one good,new my one
17.This advice is different from_____.
A.that one B.that C.it D.the one
18.The books on the table are more than____ on the bookshelf.
A.they B.them C.those D.ones
19.A cake made of wheat costs less than____ made of rice.
A.one B.it C.those D.that
20.Do you like red ink or_____?
A.blue one B.blue C.the blue one D.red ink
21.The step you’ve taken is_____ of much risk.
A.one B.that C.it D.ones
22.I’m told you’ve got some foreign stamps. Will you please give me_____?
A.one B.it C.that D.the one
五、so的用法
1、so表示替代常用来代替上文中出现的内容，尤其是上文内容在下文中以宾语从句形式出现时。
2、如果在下文被代替者为否定含义的宾语从句，常用否定动词+so或直接用not代替。如：
1. —The boys are not doing a good job at all, are they?
—______.(NMET2003 Beijing spring,22)
A.I guess not so B.I don’t guess C.I don’t guess so D.I guess not
2. —Do you think it’s going to rain over the weekend?
—_____.(NMET94,13)
A.I don’t believe B.I don’t believe it C.I believe not so D.I believe not)
3. —Do you think it’s going to rain again? —I _____, but I _____.
A.think not,hope so B.not think,so hope C.don’t think so,don’t hope so D.think not,hope not
4.—Do you think it’s going to be fine ? --Yes, and I______.
A.expect that B.expect so C.expect it D.expect them
5.—Will they come back again? --No, I_____.
A.don’t believe B.not believe C.believe not D.don’t believe that