clearance of span

例句：

1. 1. Thebridge spans the river.
   这座桥横跨河流。
2. 2. The span of time between two eventsis known as the interval.
   两个事件之间的时间间隔被称为间隔。
3. 3. The span of timefor this project is three months.
   这个项目的持续时间是三个月。