The advantage of school uniforms is that they can prevent danger from outsiders who do not wish well because when outsiders enter the school. We can distinguish who is a student and who is an outsider.
The advantage of school uniforms is that they can prevent harm from outsiders, because when outsiders enter the school, We can distinguish between students and outsiders.
The advantage of student suit is that it can prevent the danger brought by outsiders, unfortunately, because when outsiders enter the school, we can tell who is a student and who is an outsider.