a.

1. 确凿的，无疑的；可靠的
2. 确信的，有把握的；一定会的[F][（+of/about）][+（that）][+wh-][+to-v]
   They are certain to succeed. (They are certain of success.) (They are certain that they will succeed.)

   他们确信会成功。

   I'm quite certain of that.

   对那事我完全可以肯定。

   I was certain that he had seen me.

   我肯定他已看见了我。

3. 某，一位姓……的（人）[B]
   A certain person called on you yesterday.

   昨天有个人来拜访过你。

4. 某种（或一定）程度的[B]

pron.

1. 某几个；某些[（+of）]

adj.

1. able to be firmly relied on to happen or be the case.
2. completely convinced of something.
3. specific but not explicitly named or stated:
   certain problems.
   ▸not known to the reader or hearer:

   a certain Mr Percy.

pron.