"Fighting is not allowed in class" 是一个比较常见的表述。来源可能是学校或老师为了维护教学秩序而制定的规则。
例句：
Fighting is not allowed in class. 打架不准在课堂上进行。
Students are expected to follow the rules, including the rule that fighting is not allowed in class. 学生应该遵守规则，包括上课不准打架的规则。
The teacher reminded the students that fighting is not allowed in class and that they should focus on their studies instead. 老师提醒学生们不能在课堂上打架，应该专心学习。