one的用法

''one''的用法归纳起来有下列几种

一、作数词用。

1. 具有形容词性，有“一”之意。如：

one half一半；one or two days一两天

I only have one thing to stay.

此时one比a语气强些。

2. 具有名词性，有“一；一个；一个人”等意。如：

How many sisters do you have? I have one.

One of the boys is not here.

此外，one用在名词后，“第一”的意思。如：

No. one , Page One, Picture One

二、作形容词用。

1. 与表示时间的名词连用，构成副词性词组，作“某一”，“有一”等解时，其前不加介词。如：

one morning(night)有个上午(晚上)，one Friday有一个星期五

注意，one day既可指过去“有一天”，也可指将来“有朝一日”。细读下面两句子：

One day a young man came to see me.

One day we'll go to the moon by spaceship.

注意区别下面两个句子，前一句用one，前面不加介词；后一句用a，前面加了介词。

One summer afternoon I met him in the street.

One a summer a afternoon I met him in the street.

2. 有"the same''之意，即“同一的”“一致的”。如：

in one voice异口同声地 ; one price一样价钱

It is all one to me. 这对我是一样的。

3.有“（作对比）一方的”意思。如：

from one side to the other从一头到另一头

To say is one thing and to do is another 说是一回事，做又是另一回事。

三、作代词用。

1. 作不定代词，有“任何人”，“谁都”的意思。如：

One must love one's (his) country谁都必须爱国。

One for all and all for one.个人为集体，集体为个人。

2. 代表人称代词，“个人”，“某人”之意。如：

run as fast as one can尽量跑得快马

do one's best 竭尽所能，尽力

3. 作“一个”，“一本”，“一件”等解，用来代替上文提到过的某个可数名词，以避免重复，其前不加任何限定词。如：

My pen is broken. I must buy one.

''Have an apple, please."

"No, thanks. I've just had one."

注意：one与it都可替代上文出现的某个名词，但用法不同。one用来指代上文出现的某类物中的一个，it指代上文中出现的那个物。细读下文，仔细比较：

1) A: Do you have a knife?

B:Yes, I have one.

A: Give it to me ,please. B: OK. Here it is.

2) A: Do you have any pencils?

B: Yes, I have one.（此时复数形式用some）(Yes, I have some.)

3) A: Would you like the watch? B: Yes, I'd like it.

4. one与形容词连用时，其前常有a, the, this, that, next,last, my, her等限定词。如：

a small one, the blue one, my new one, his big one, your old one（one前有形容词修饰时，才可以与形容词性物主代词或名词所有格连用。如：Jim's new one)

5. one可以与疑问代词(which)、相互代词及序数词连用。如：

1) Which one is yours?

2) This one is too heavy. Give me another one.

3) The second one is bigger.

6. one的复数形式为ones。但要注意：ones只有在其前修饰语时才能用。如：

Which ones are theirs? The blue ones are theirs.

I want big ones, I don't want small ones.

7. 作对比用时，one为“一个、一方”之意。如：

1) There are two(three) balls. one is yellow. The other is (The others are) black.

2) This is my sock. The other one is under the desk.

8. these ones与those ones很不普通。如最好不说：These ones are not good. I want those ones.要说：These are not good. I want those.

高考中常常考查one和that作为普通代词的区别，还常与it进行区别。主要用法如下：

it／one ／that三者均可用作代词, 指代前面提到的名词。一般说来, it指代同名同物; one与that则指代同名异物。
I have lost my umbrella; I'm looking for it. （该句中it就是指前面的my umbrella）
I have lost my umbrella; I think I must buy one. （one在该句中表泛指, 因为my umbrella已经丢了）
The umbrella you bought is cheaper than that I bought. （替代词that在该句中特指“the umbrella I bought”, 以区别“the umbrella you bought”）

II. one与that虽可用来指代同名异物, 但one为泛指, 相当于a／an＋名词; that为特指, 相当于the ＋名词。所以one所指代的名词的修饰语一般为 a／an ／some ／any; that所指代的名词的修饰语往往是the ／this ／that。
A chair made of steel is stronger than one made of wood. （该句中one可以换成a chair）
The water in the cup is hotter than that in the pot. （该句中that可以换成 the water）

III. one只能代替可数名词单数, 代替可数名词复数时用ones; that既可以代替不可数名词也可以代替可数名词单数, 代替可数名词复数时用 those。
I like this pen more than that one. （one代替可数名词单数pen）
There were a few young people and some older ones in the house. （ones代替可数名词复数people）
Mary's handwriting is far better than that of Peter. （that代替不可数名词 handwriting）
These pictures are more beautiful than those. （those代替可数名词复数 pictures）

IV. one既可代替事物, 也可代替人, that只能代替事物而不能代替人。有时可以用the one或the ones代替that或those。
The one ／That on the table is mine. （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）
He advised the farmers to choose the best seed-heads, the ones ／those that had the best color. （该句中the ones代替事物, 并且也可以用those）

V. one一般有前置修饰语, 有时也可有后置修饰语或不用修饰语。而 that不能有前置修饰语, 但可有后置修饰语。
Cook was a strict but good captain, one who took good care of his sailors.
The water in the well is cleaner than that in the river.
VI. it可以替代句中的不定式或从句等, 充当形式主语或形式宾语。one与that均无此用法。
It is known to everybody that the moon travels around the earth once every month.
I found it hard to get on with her.

VII. it与that均可以替代上文全句的内容或部分内容, 而one ／ones则不可以。
He has saved my life; I'll never forget it. （it代替第一分句）
Tom is painting his house. I am told he does it every four years. （it代替前面分句的部分内容painting his house）
Let's say we meet here at three o'clock. That ought to give you time to buy everything. （That代替前面表述的内容

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