adj. 某一；必然的；已确定的；
pron. [动词用复数]某些；
1. be certain of [about] sth 对某事有把握或感到自信。如：
He’s certain of success. 他自信会成功。
Are you certain of [about] that？ 你对此有把握吗？
2. be certain to do sth 肯定会发生某事。如：
She’s certain to pass the exam. 她考试肯定会及格。
Spring is certain to follow winter. 冬季过后一定是春天。
注：该结构有时可用 I am certain that 来转换。如：
He is certain to come. / I am certain that he will come. 他肯定会来。
3. be certain of doing sth 确信会发生某事。如：
He is certain of winning the match. 他确信能赢这场比赛。
注：该结构有时可与后接 that 从句的句型转换。如：
He is certain of passing the exam. / He is certain that hecan pass the exam. 她确信考试会及格。
4. for certain 有把握，肯定地。如：
I don’t know for certain. 我知道得不确切。
I can’t say for certain when he will come. 我不敢肯定地说他什么时候来。
5. make certain 弄清楚，弄得有把握，核实。如：
(1) 单独使用。如：
I think the train leaves at six o’clock but you ought to make certain. 我想火车是六点开吧，但你应该查清楚。
(2) 后接 that 从句。如：
Make certain (that) you know what time the train leaves. 你要弄清楚火车开出的确切时间。
(3) 后接 of 短语。如：
You must make certain of the date of the meeting. 你必须把开会的日期弄清楚。
We went to the theatre early and made certain of getting seats. 我们去戏院很早，以便可弄到座位。
注：有时以上各结构可互相转换。如：
Make certain of his safe arrival. / Make certain that he arrived safe. 弄清楚他是否安全抵达了。
1. There is a certain impatience among some of the soldiers.
有些士兵有点儿不耐烦。
2. Over the years he's demonstrated a certain prescience in foreign affairs.
这些年来，他已经在外交事务方面表现出一定的预见性。
3. I feel certain that it will all turn out well.
我觉得最后肯定会皆大欢喜。
4. There are certain things he does that drive me mad.
他的某些举动让我很生气。
5. Parents can programme the machine not to turn on at certain times.
父母可以设定这台机器的程序，使它在特定时间段无法开启。
6. The stores are sometimes sold out of certain groceries.
有时商店里的某些杂货会有脱销的现象。