If you are unsure of yourself, you lack confidence.
The evening show was terrible, with hesitant, unsure performances from all.
晚上的演出很糟糕,所有表演者都缩手缩脚,缺乏信心。
If you are unsure about something, you feel uncertain about it.
Fifty-two per cent were unsure about the idea.
52的人都不看好这个主意。