downward bulge

例句：

1. 1. The car's engine has a downward bulge in the front.
   这辆车的引擎在前部有一个向下凸起。
2. 2. Theroad is downturningdue to heavy rain.
   由于大雨，道路正在下陷。
3. 3. The depressionin the ocean caused by the icebergwas quite large.
   冰山引起的海啸造成的海底下陷相当大。