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In the classroom, students often leave the used tissue or other unwanted things around their seats instead of putting them into the rubbish bin. Perhaps they think that it is the responsibility of the janitor or the one on duty to clean up the classroom.
In the canteen, we may also find some empty cans or boxes of soft drinks, and the snacks not eaten yet on the tables or on the ground.
The toilet may be dirty too. Some naughty may even use toilet paper as "toys".
2008-06-06 17:14:58 補充:
some naughty STUDENTS ...