kuan

例句：

1. 1. The width of the river is about 20 meters.
   这条河的宽度大约是20米。
2. 2. The range of the moonlight is visible from here to there.
   月光的范围从这里到那里都是可见的。
3. 3. The span of time between two events is known as a gap.
   两个事件之间的时间跨度被称为间隙。