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。小编今天就迎难而上，为大家搞定这几个考点。
基本概括就是，it指代的是特指同类同物；that指代的是特指同类异物，常常用于同类的事物之间的比较；one指的是（泛指）上下文中提到的同类事物中的一个。以下是具体的区别：
1.one, it, that常常用来代替或避免重复某个名词。例如：
I'm looking for a flat. I'd really like one with a garden.
我在找一套公寓。我好想要一个带花园的公寓。
Where did you find your watch? - I find it in our classroom.
你在哪里找到你的手表的？我在教室里找到的。
The population of China is larger than that of any other country.
中国的人口比任何其他国家都多。
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：
One can fly to New York in three hours. （one=anybody）
坐飞机三个小时就可以到达纽约。
One must do one's duty.（one=anybody）
每个人必须尽自己的责任。
Mary has a red pencil and Jane has a blue one.
玛丽有一支红铅笔，简有一支蓝铅笔。
The new designs are much better than the old ones.
新设计比旧设计好得多。
I can't find my hat. I think I must buy one. 我找不到我的帽子了。我想我该去买一顶。
A chair made of steel is stronger than one made of wood.
钢做的椅子比木头做的椅子结实。
（该句中one可以换成a chair）
The one ／That on the table is mine. 桌上的那个是我的。
他就是那个老师，是学生们喜爱的那个老师。
（该句中The one代替事物，并且也可以用That）
He is the teacher, the one who is loved by the students.
（该句中the one代替人，不能用that）
I like this pen more than that one.
我喜欢这支钢笔超过喜欢那支钢笔。
（one代替可数名词单数pen）
I have lost my umbrella; I think I must buy one.
我把伞丢了；我想我必须买一个。
（one在该句中表泛指，因为my umbrella已经丢了）
There were a few young people and some older ones in the house.
房子里有几个年轻人和一些老年人。
（ones代替可数名词复数people）
one可以代替与前面同类不同一的事物；可以代替某类事物中的任何一个；可以做同位语，重复指代前面的事物，其后有定语从句用以进一步说明前面的名词。
Somebody(Someone) is knocking at the door.有人在敲门。
这里的Somebody(Someone)不能用One，因为这个敲门的人显然不包括说话人和听话人在内。
Meeting my uncle after all these years was an unforgettable moment，______ I will always treasure.
A.that B.one C.it D.what (高考真题)
答案是B，one后面省略了充当treasure宾语的that；而one又是an unforgettable moment同位语，且I will always treasure又是one的定语从句。
注意：
one表泛指，相当于a/an 名词。
one只能代替可数名词，其复数形式是ones。
one可以根据语义在它的前面或后面加上一些定语。
one前面不能直接加不定冠词（a / an）或物主代词，one前已经有形容词时，则可以加不定冠词或物主代词；one前加the与否，取决于是否特指，如果特指就加the。
one既可以代指物，也可以代指人。
Our original plan was overtaken by events and we had to make a new one.
我们原来的计划没赶上变化，只好再订一个新的。
If the door is warped, you'd better buy a new one.
如果门变形了，你最好买个新的来。
Bury the old world and build a new one.
埋葬旧世界，建设新世界。
The light bulb in the bathroom burned out and father put in a new one.
洗澡间里的灯泡烧坏了，父亲装上一只新的。
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。常常用于同类的事物两个或几个之间的比较。如：
The library of our school is bigger than that of yours.我们学校的图书馆比你们学校的图书馆大。
(that代替的是另一个图书馆，相对来说也是具体的特指的某图书馆。)
The climate here is said to be like that of Tokyo.据说这里的气候和东京的气候相像。
that指代的是 the climate （of Tokyo）,明显表示的是特指。
The population of Shanghai is larger than that of Beijing.上海的人口比北京的多。
That指代的是the population of Beijing，明显表示的是特指。
The weather today is warmer than______ yesterday.
the one B.one C.that D.which
答案为C，明显是同类异物之间的比较，that指代的是 the weather yesterday.
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。简单的说，就是one相当于an/a 名词，that相当于the 名词。例如：
I will take the seat next to the one(=that)by the window.我将坐靠近窗口那个座位的隔壁座位。
I prefer the large box to the small one.(one 不可用that替换 )。
我喜欢大盒子而不是小盒子。
The water in the cup is hotter than that in the pot.
杯子里的水比锅里的水热。
（该句中that可以换成 the water）
Mary's handwriting is far better than that of Peter.
玛丽的书法比彼得好得多。
（that代替不可数名词 handwriting）
These pictures are more beautiful than those.
这些画比那些画漂亮。
（those代替可数名词复数 pictures）
He advised the farmers to choose the best seed-heads, the ones ／those that had the best color.
他建议农民选择最好的种穗，那些最好的种穗具有最好的颜色。
（该句中the ones代替事物，并且也可以用those）
The hat you bought is bigger than that I bought.(同类但不同个)
你买的那顶帽子比我买的大。
that代替与前面同类不同一的事物。that是特指，相当于the 名词。它可以代替可数名词，也可以代替不可数名词。代替可数名词时，复数形式为those。that可以根据语义在它的后面加上一些定语，多数是of短语；它的前面不能存在任何定语。并且that只能代指物。
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：
Today's cellphones are smaller than those(=the ones)used in the past.
今天的手机比过去用的小。
The students who do best in exam are not always those(=the ones) with the best brains.
考试成绩最好的学生并不总是那些头脑最聪明的学生。
I think you'll find these more comfortable than those.
我想你会觉得这些比那些更舒适。
Salaries are higher here than those in my country.
这里的薪水比我国的高。
Traditionally reared animals grow more slowly than those reared under intensive farming conditions.
按传统方式饲养的家畜比集约饲养的长得慢。
Such people often experience less stress than those in the ranks immediately below them.
这些人承受的压力往往小于那些职位仅次于他们的人。
Vitamins in solution are more affected than those in solid foods.
溶液里的维生素比固体食物里的维生素受到的影响更大。
Many patients prefer hand-held shower heads rather than those fixed to the wall
很多病人更喜欢手握式的淋浴喷头而不是固定在墙上的那种。
Farms in France are much smaller than those in the United States or even Britain.
法国的农场比美国甚至是英国的农场都要小很多。
Southerners smoke less and drink less than those in other parts of the country.
与这个国家其他地方的人相比，南方人抽烟和喝酒都比较少。
Gardens on the windward side of a hill receive more rain than those on the lee side.
山坡向风面的花园比背风面的雨水多。
The goods in this mall are more expensive than those in other places.
这家商场里的商品比其他地方贵。
The enemy hidden in our ranks are of course much more dangerous than those acting in broad daylight.
隐藏在我们队伍中的敌人当然要比明火执仗的敌人更加危险。
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：
Their problem today is somewhat similar to that which they faced many years ago.
他们今天的问题与多年前的问题有些相似。
The true cost often differs from that which had first been projected
实际成本经常与最初计划的有所不同。
The United States will do that which is necessary to meet its obligations to its own citizens
美国将为自己的公民尽其应尽的义务。
My teaching style is similar to that of most other teachers.
我的教学风格和多数教师相似。
The basic design of the car is very similar to that of earlier models.
这种汽车的基本设计与早期的样式非常相似。
The school's approach must be complementary to that of the parents.
学校与家长的教育方法必须相辅相成。
Europe's foreign policy is inextricably linked with that of the US.
欧洲的对外政策和美国的紧密相扣。
The present position of the house coincides with that of an earlier dwelling.
这栋房子现在的位置恰与原住宅的位置一致。
The US air travel market dwarfs that of Britain.
与美国航空旅行市场比起来，英国的航空旅行市场相形见绌。
7.代替不可数名词时，应该用that。如：
The equipment is different from that.
这个设备和那个设备不一样。
The population of China is larger than that of Japan.(that代替不可数名词population,不可用the one替换)
中国的人口比日本多。
The headteacher in your class is younger and more active than that in theirs.(that代替可数名词headteacher,可用the one替换)
你们班的班主任比他们班的班主任更年轻、更活跃。
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. 我的钢笔丢了。我在找。（该句中it就是指前面的my pen）
I have lost my umbrella; I'm looking for it.
我把伞丢了；我在找。
（该句中it就是指前面的my umbrella）
I can't find my hat. I don' t know where I put it. ( 同一物)
我找不到我的帽子。我不知道我把它放在哪了。（该句中it就是指前面的my hat）
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。
He said he had never met her,and it is not true.(it替代前面整个句子He said...)
他说他从未见过她，这不是真的。
I hate it when people talk with their mouths full.(it代替后面整个句子when people talk with...)(NMET'98)
我讨厌人们满嘴食物说话。
He may come or may not come .I am not too sure about that.
他可能来也可能不来，我对此不太确定。
that指代前面一个句子
He always goes to work late ,which makes his boss angry and disappointed.
他总是迟到，这使他的老板既生气又失望。
Which引导非限制性定语从句，指代前面一个句子。
