例句：
In those days most people left school when they were only fifteen years old.
那时候，大多数人上学只上到十五岁。
The wiring in your house should be renewed every ten to fifteen years.
你家里的电线应该每十到十五年更新一次。
The room measures fifteen feet by twenty feet.
房间15英尺宽20英尺长。