阅读短文,One day after school the teacher says to his students,“

阅读短文,
One day after school the teacher says to his students,“Tomorrow morning,if anyone of you can answer my first question．he or she can go home early．”
The next day,when the teacher comes into the classroom,he finds the blackboard is very dirty．He is very angry and asks,“Who did（做）it?Please stand up!”“It’s me,”says Bob,“Now I can go home．Good bye,sir．”
1、 what can the student do if he can answer the teacher's first question?
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2、What does the teacher ask when he sees the dirty blackboard?
She asks,"__________________________________________"
3、Who answers the question?
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4、Does the teacher ask Bob to go home?
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