span saw

例句：

1. 1. The span of the bridge is 200 meters.
   这座桥的跨度是200米。
2. 2. The span of time between two events is known as a gap.
   两个事件之间的时间称为间隙。
3. 3. The span of this book is 500 pages.
   这本书的篇幅是500页。