【单选题】The average number of hours of sleep that a child needs is 10 hours,while an adult needs is 7 hours. The average number of hours of sleep that an adult needs is _____.
【简答题】The average number of hours of sleep that a child needs is 10 hours,while an needs is 7 hours. The average number of hours of sleep that an needs is _____.A. approximately six hours B. ...