gradient of neutrons

例句：

1. 1. The slope of the mountain is steep.
   这座山的坡度很陡。
2. 2. The car's speed increases with the gradient of the road.
   汽车的速度随着道路的坡度增加而增加。
3. 3.The gradient of the river changes from low to high as it flows downstream.
   这条河流在下游时，其流速从低到高变化。