it

（指代同名同物）

it 指代上文所提事物的本身，如果所代替的事物为复数，则应该用 they 或 them 表示

The Parkers bought a new house but it will need a lot of work before they can

move in.

it 也可以用来代替上文所提到的一件事

Mary’s mother always told her to work

hard, but it didn’t help.

see to it that=see that/make sure that/check that 意思是“确保”“务必”，这里所提到的 that 从句中的将来时都要用一般现在时替代。

You will see to it that your methods are ideal.

that

（指代同名异物）

that 表替代时是特指，可指上文谈到的物或情况（均为单数，可代替可数名词和不可数名词，有时 that 后面接 of 短语）

—He was nearly drowned once.

—When was that?

His car is quite different from that of hisbrother’s.

one（既可代替事物， 也可代替人）

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（而 that代替上文谈到的物或情况）， 且被替代者为可数名词单数形式，相当于“a+名词”

（泛指），其复数形式为 ones

I don’t like this skirt, please show me another one.

Meeting my uncle after all these years

was an unforgettable moment, one I will alwaystreasure.

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 形式表示；若下文替代时为复

数含义，则用 the—adj—ones 或 the ones 表示

I brought a necklace to you that day but it was a differentone.

I don’t like this blue cat, I’d like the red

one.

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

Did you hear the one about the famous mathematician?

She locked her old ones in the box.

He was angry, and his wife was even

more so.

—Do you think it’s going to rain over the weekend?

—I don’t believe so. / I believe not.