Xiao Ming arrives at school every morning at 8:00, leaves school at 10:30, arrives at school at 12:00 pm, and leaves school at 4:30 pm. How many hours does Xiao Ming spend at school every day?
小明每天上午8：00到校，10：30放学，下午12：00到校，下午4：30放学，小明每天的在校时间为多少小时．
<result>7</result>