level ridges

例句：

1. 1. The level of theriver has dropped significantly since the flood.
   自从洪水过后，河流的水位大幅下降。
2. 2. Thelevel of education in this area is stilllow compared to other countries.
   与其他国家相比，该地区的教育水平仍然较低。
3. 3. The levelof the ocean is affected by the tides and currents.
   海洋的水平面受到潮汐和洋流的影响。