问题补充：
I often exercise for three hours every day 对three划线提问
答案：
How many hours do you exercise every day?
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======以下答案可供参考======
供参考答案1:
how many hours do you often exercise every day?
供参考答案2:
How many hours do you often exertise every day ?
供参考答案3:
How long do you often exercise every day
