能量管理系统工作原理:Jack spends two hours _____housework.

Jack spends two hours _____housework. My mother usually spends more than half an hour cleaning the house.(划线部分more到hour) 改错:My brother spends two hours to go to school by bike every day. One hour today is worth two tomorrow.争分夺秒效率高 请问“两个半小时”是“two and a half hour”还是“tow and a half hours”？ VOA一开始的one/two/fifteen hour universal time 是什么意思 What ( ) two plus two ? every hour on the half hour是什么意思? every hour on the half hour 是什么意思？ half an hour 与a half hour