1.Everyone must pick up their rubbish and put it in the rubbishbin when leaving the class.You mustn't leave any rubbish behind.
2.Cellphones must be turned off during class.
3.Uniforms must be correctly worn.
4.Eveyone must be silent while the teacher is talking.The teacher should not have to talk over the students.
5.Everyone must do what the teacher says,must not disorbey the teacher.
6.Mustn't fight each other,must be friendly to each other.
7.Must do your homeworks.
8.Everyone must obey these rules!
不知到有没有50字.想到的只有这些.我想这些应该有50吧.