At school,we have to (clean the blackboard).对划线部分提问

题目

At school,we have to (clean the blackboard).对划线部分提问
_____ ______ you have to _____ at school.

答案

(What do) you have to (do) at school?
解释：因为这里要提问的是clean the blackboard,所以要用what来提问.