1. 表示说话者的态度或看法


(1) 单独用作表语。如:

One thing was sure [certain]: they’d be late. 有一件事是确定无疑的,他们会迟到。

(2) 后接不定式。如:

He’s certain [sure] to win. 他一定会成功。

They’re certain [sure] to need help. 他们肯定需要帮助。

If you do this, you are certain [sure] to be found out. 如果你这样做一定会被发现。

2. 表示句子主语的判断或信念


(1) 后接of [about] sth。如:

He is certain [sure] of success. 他确信会成功。

Are you certain of [about] that? 你对此有把握吗?

(2) 后接 of doing sth。如:

Our team is certain [sure] of winning. 我们队有把握赢。

You can be sure [certain] of his agreeing. 你可以放心他会同意。


He is certain [sure] of winning.

=He is sure [certain] that he will win. 他自信会赢。

(3) 后接 that / whether / if 从句。如:

I am sure [certain] that he is honest. 我肯定他是诚实的。

I’m sure [certain] that it’s not your fault. 我敢肯定这不是你的错。

Are you certain [sure] that this is the right road? 你肯定这条路对吗?

注:当be sure [certain]为肯定式或疑问式时,后接that从句;当be sure [certain]为否定式时,后接whether [if]从句。如:

I’m not sure [certain] whether he still works there. 我不能肯定他是否还在那里工作。

I wasn’t sure [certain] whether he would agree. 我不太肯定他是否会同意。

He wasn’t sure [certain] whether he would be able to get back in time. 他不能肯定他是否能准时回来。

(4) 后接其他从句。如:

I’m not sure [certain] where she lives. 我不能肯定她住在哪里。

I’m not certain [sure] who wrote it. 我不太清楚这是谁写的。



1. 当句中用了形式主语或形式宾语 it 时。如:

It’s certain that he’ll come tomorrow. 他明天肯定会来。

I thought it certain that he would be late. 我肯定他会迟到。

It’s certain that prices will go up. 价格肯定会上涨。

It’s not certain how much it will cost. 这要花多少钱还不确定。

2. 当表示“某一”“某些”时。如:

A certain Mr Green wants to see you. 有个叫格林先生的人想见你。

Certain plants are good to eat but others are not. 有些植物好吃, 而其他一些则不好吃。


在 Be sure (not) to do sth.(一定要或不要做某事)这类中通常不用 certain。如:

Be sure not to forget it. 千万别忘记啦。

Be sure to get there before nine. 务必在九点前到达。

Be sure to turn off the light when leave. 离开时一定要关灯。


1. 用于 for certain / for sure, 意为“肯定地”“确切地”等,两者可互换。如:

I can’t say for certain [sure] when he will come. 我不敢肯定地说他什么时候来。

No one knows for sure [certain] what happened to her. 没有人确切地知道她出了什么事。

2. 用于 make certain / make sure,意为“弄清楚”“弄得有把握”,两者可互换。如:

They made certain [sure] (that) they weren’t late. 他们有把握不迟到。

I think there’s a train at 10:40, but you’d better make certain [sure] of it. 我想10:40有趟火车,但你最好去核实一下。