定然

例句：

1. 1. I'm sure you'll do well in this exam.
   我确信你在这次考试中会做得很好。
2. 2. He certainly knows more about the subject than anyone else.
   他确实比任何人都更了解这个科目。
3. 3. You can be certain that she will arrive on time.
   你可以肯定她会准时到达。