1 [pred 作表语] ~ (that...); ~ (to do sth) sure beyond doubt; that can be relied on 无疑; 确定
*It is certain that he will agree/He is certain to agree. 肯定他会同意[他一定同意].
* One thing is certain
*I'm not coming here again. 有一件事可以肯定, 我再也不来了.
2 [pred 作表语] ~ (that...); ~ (of/about sth) positive in one's mind; completely sure 确信; 肯定
*I'm certain (that) she saw me. 我肯定她看见我了.
* She saw me
*I'm certain of that. 她看见我了, 这一点我可以肯定.
* I'm not certain (of) what she wants. 我不清楚她想要什么.
3 [attrib 作定语] sure to come, happen or be effective; assured 一定会来到、发生或生效的; 有把握的
*There is no certain cure for this disease. 这种病没有特效药.
* They face certain death unless they can be rescued today. 他们除非今天获救, 否则必死无疑.
4 [attrib 作定语] specific but not named or stated 某（不指明的或不说出的）
*For certain reasons I will be unable to attend the meeting. 因为某种原因, 我不能出席这次会议.
* The terrorists will only release their hostages on certain conditions. 恐怖分子只有在某些条件下才释放人质.
5 [attrib 作定语] named but not known 说出姓名但不认识的
*A certain Mr Brown telephoned while you were out. 你出去的时候, 有个叫布朗的先生来过电话.
6 [attrib 作定语] slight; some 稍微的; 一些的; 一点儿的
*There was a certain coldness in her attitude towards me. 她对我的态度有点儿冷淡.
* I felt a certain reluctance to tell her the news. 我不太愿意告诉她这个消息.
7 (idm 习语) for `certain without doubt 无疑地; 确定地
*I couldn't say for certain when he'll arrive. 我说不准他什么时候到.
* I don't yet know for certain. 我知道得不确切. make certain (that...) inquire in order to be sure about sth 弄清楚; 弄明白; 弄确实
*I think there's a train at 8.20 but you ought to make certain. 我想8点20分有一班火车, 不过你应该打听清楚. make certain of sth/of doing sth do sth in order to be sure of (doing) sth else 采取行动以便确有把握做其他事
*You'd better leave now if you want to make certain of getting there on time. 你要想准时到达那里就最好马上走.
pron ~ of... some particular members of (a group of people or things) （人或物中的）某些
*Certain of those present had had too much to drink. 有些出席的人喝得太多了.
NOTE ON USAGE 用法
*Sure and certain are often used in the same way *sure和certain的用法常常是相同的
*They're sure/certain to be late. 他们一定迟到.
* I'm sure/certain (that) they'll be late. 我肯定他们得迟到.
* One thing was sure/certain
*they'd be late. 有一件事是确定无疑的, 他们得迟到.
* They made sure/certain (that) they weren't late. 他们有把握不迟到. With `it' as an indefinite subject or object only certain can be used *it作不定主语或不定宾语时, 只可用certain与之连用
*It was certain/ I thought it certain that they would be late. 肯定[我肯定]他们要迟到. Sure can sound weaker than certain, especially in conversation *sure的语气听起来比certain弱些, 特别是在对话中
*I'm sure he'll manage it, ie I think/hope he will. 我确信他能办到（即我认为[希望]他能办到）.