形容詞 unsure:

1. lacking or indicating lack of confidence or assurance
   同義詞：uncertain, incertain
2. lacking self-confidence
   同義詞：diffident, shy, timid

1. Beneath her self-confident surface, she's quite unsure of herself.
   她看上去信心十足，實際上很缺乏信心。
2. As if unsure of where she was, she hesitated and looked round.
   她彷佛茫然不知身在何處，猶猶豫豫向四周打量。

un.sure

adj.（形容詞）
Lacking confidence.
缺乏自信的
Uncertain of the facts.
不確定事實的
Precarious; unstable; unreliable.
不穩(wěn)定的，不固定的；不可信任的；不可靠的

【引伸】
unsure.ly
adv.（副詞）