Definition
To be confident or certain that something is true.
确定，确信
I'm not sure of finishing this report on time.
我不确定能否准时完成这份报告。
She was sure of her answer.
她对自己的答案很有把握。
We can’t send out the invitations until we are sure of all the arrangements.
在我们确定所有安排之前，我们不能发出邀请。