К этому предложению можно задать следующие вопросы:
1. Students wear school uniform at school, don't they?
2. Who wears school uniform at school?
3. What uniform do students wear at school?
4. What do students wear at school?
5. Where do students wear school uniform?
6. (Ну совсем уже тупой вопрос) What do students do at school?
7. Do students wear school uniform at school?