答案：
Possible version:
Our school has made a survey about how long middle school students can fix their attention in class during each period. The result shows that only 40% of the students can draw their attention to their class, while the rest of them can not concentrate on the lesson. 30% of the students think the problem is caused by all kinds of noises in the classroom; the other part of students consider lack of sleep and tiredness as the major causes.
Therefore, we advise that the classroom be bright and the air inside stay fresh. As for students, they should try their best to be active in class in order not to be disturbed by others. During the breaks, they can take some exercise or have a little rest in the classroom. Also, it is necessary to balance their diet. Talking to the classmates may also help them relax. Keep in mind that all work and no play make you achieve less in your studies