平坦的

The river slows on the flat bottom.

河水的河床上减慢了流速。

Various vehicles bowl along over the smooth highway.

各种车辆的高速公路上疾驶。

The rim is flat and there is a rather deep well, or cavetto.

边缘是的，有一个相当深的底部，或称圆底。

Heading away from the mountains, I soon found an easier path leading downhill to the village.

我背着山走了不久, 就发现了一条通往该村比较的下山小路。