B2 behaving calmly because you have no doubts about your ability or knowledge

中文解释

自信的，信心十足的 At school he was popular and self-confident, and we weren\'t surprised at his later success. 在学校的时候，他很受欢迎又很自信，所以对他以后的成功我们丝毫不感到惊讶。