Her effrontery to contradict the teacher in public was unbelievable.

### 解释 effrontery 是名词，来自法语 effronterie，指"厚颜无耻、放肆无礼的行为"。这个词带有强烈的负面含义，形容某人做出令人震惊的无礼或冒犯行为时毫无羞耻感。