(1) ①sure 意为“一定的，必定的；有信心的；无疑的；确知的”，多作表语，有时也作定语。
- I think so, but I'm not sure .
我想是这样，但我不敢肯定。 - One thing is sure , that is, the Chinese team will win the championship.
有一件事可以肯定，那就是中国队将获得冠军。 - Are you sure whether he will come to the party?
你能肯定他一定会前来参加聚会吗？
②sure可接about或of，表示“对……有把握”，是某人自己(通常用作主语或逻辑主语)的一种确信或判断。
- I don't feel quite sure of that.
对那件事我感到没有确切的把握。 - Not being sure of the word, he looked it up in the dictionary.
由于对这个单词没有把握，他查了一下字典。 - I'm not quite sure of/about his ability to cope with such matters.
我对于他处理那类事情的能力没有太大的把握。
③sure接不定式，表示“一定会，准会”，是说话人的判断。
- Believe it or not, in any case the truth will be sure to come out.
信不信由你，不管怎样，真相一定会水落石出的。 - He is sure to have left here for Qingdao.
他肯定是已经离开这里去了青岛。 - Don't put him in charge of planning; he is sure to fall down on the job.
别让他负责筹划工作；他肯定是干不好的。
④sure有时作定语用，表示“有把握的，可靠的，肯定的”。
- There is no sure remedy for this disease.
对这种疾病没有可靠的治疗方法。 - Put your glasses in a sure place.
把你的眼镜放在妥当的地方。
(2) ①certain表示“有把握的，肯定的”，多作表语，也作定语。通常可与sure换用。
- I'm perfectly certain/sure (that) he appreciated every item of this little performance.
我非常肯定他对这个小型表演的每一个节目都非常欣赏。 - I'm not quite certain/sure whether we'll be able to use their recording equipment.
对于我们能否用他们的录音设备，我没有太大的把握。
②certain也可接of或about表示“对……有把握”，与sure可换用，表示主语或逻辑主语的确信或判断。
- We'll be happy with him, and I'm quite certain of that.
我们与他在一起将会非常愉快，对此我很有把握。 - I'm not certain of/about his coming.
他是否来，我没有太大的把握。
③certain接不定式，表示“一定会，肯定会”，表示说话人的判断。
- He is pretty certain to come to the party. (He will certainly come to the party.)
他肯定会来参加宴会。 - The duties before me are certain to be heavy.
摆在我面前的任务一定会很重。
④certain用于其他结构。
- Is it quite certain or is it not yet decided?
这已十分确定还是尚未定下来？ - It is almost certain that he will lose the next election.
几乎可以肯定，他将在下次选举中失败。
⑤certain用作定语，表示“一定的，确定的，可靠的”。
- Scientists have found a certain cure for the disease.
科学家已发现了治疗这种疾病的一种可靠的疗法。
⑥certain用作定语，还可表示“某人，某些，某种”。
- We can send a certain person there to handle this matter.
我们可以派某个人前去处理此事。 - To a certain degree/extent, it will serve our purpose.
它在某种程度上合乎我们的意图。 - He felt a certain reluctance to come to the meeting.
他感到有些不太情愿参加这个会议。
(3) ①另有make sure和make certain短语。前者意为“弄肯定，务必做到”；后者表示“弄清情况，弄得有把握，一定要设法”。两者常可换用。
- Have you made sure/certain that we'll be permitted to use the recording room?
你能肯定我们能被允许使用这个录音室吗？ - I hear the bus leaves Shenzhen at 2 p.m., but you'd better make certain .
我听说这趟汽车下午两点离开深圳，但你最好还是确认一下。 - Make sure that you haven't forgotten to pack everything you're likely to need during the camping.
一定不要忘记把你在宿营时有可能需要的每一件东西都放进包里。
②make sure和make certain之后可接of或about，与名词、代词、动名词连用，意思相近。
- Make sure/certain of all your facts in your essay.
一定要弄清楚你论文中的所有事实。 - We went to the theatre very early to make certain of getting seats.
为确保弄到座位我们很早就到剧院去了。
③be sure和be certain也有类似用法，表示“一定要做到，务必”。
- Be sure/certain you catch the bus.
你务必赶上公共汽车。 - Be sure not to forget to post the letter.
一定不要忘记寄信。
④for sure和for certain意思相近，表示“肯定地，有把握地”。
- I can't say for sure/for certain whether we can give you our decision by Wednesday.
我没有太大把握我们到星期三能否给你决定。 - He said he would give us his reply for sure in two or three days.
他说他两三天内肯定会给我们答复。
⑤for (a ) certainty, with certainty可与for sure, for certain换用。
⑥without fail意为“一定，肯定无误地”，常用于许诺、命令或要求等。
- Be here at 8 o'clock sharp, without fail .
务必8点整到这儿。 - You must let me have the car without fail by 3 o'clock tomorrow afternoon.
到明天下午3点钟，你一定要让我得到这辆车。 - He came to visit me every Sunday without fail .
每个星期天他都来看我，从无例外。
(4) ①positive也可作“肯定，有把握”解，在此意思上接近sure和certain。
- Are you positive/sure that he has not yet set off?
你肯定他还没有动身吗？
②positive也可与of或about连用。
- Can you be positive of what you saw?
你能肯定你所看到的事情吗？ - I'm not positive about it.
我对此没有太大的把握。
