许多青少年对自己的外表感到不自信。

Many teenagers feel ___insecure about their appearance.

人们感到不自信和紧张，士气下降了。

People felt ___insecure and nervous, their morale went down.

她不自信的性格常常阻止她接受新挑战。

Her ___insecure nature often prevents her from taking on new challenges.