不自信英文介绍如下：
Lack of confidence。
confidence：英/ˈkɒnfɪdəns/ 美/ˈkɑːnfɪdəns/。
n.
信心;信任，信赖;信任;自信心;信赖;把握;肯定;秘密;（向某人透露的）秘密，机密。
adj.
骗得信任的。
复数： confidences。
记忆技巧：con- 表强调 + fid 信任;信念 + -ence 性质;状态。
双语例句：
She suffers from a lack of confidence.
她深受缺乏自信心之苦。
Her confidence has been slowly eroded by repeated failures.
她的自信心因屡屡失败慢慢消磨掉了。
Self-doubt began to gnaw away at her confidence.
对自己的怀疑渐渐吞噬了她的自信心。
Those people hurt me and knocked my confidence.
那些人既伤害了我的身体又打击了我的自信心。
As her confidence grows you may well see a considerable turnabout in her attitude.
随着她自信心的增强，你很可能会看到她的态度有相当大的转变。
The more confidence you build up in yourself, the greater are your chances of success.
树立的自信心越强，成功的把握就越大。
She lost the next five games, and the set, as her confidence abruptly deserted her.
她突然自信心全失，接下来连败5局，并最终丢了这一盘。