海床是多样海洋生物的家园。

The sea ___bed is home to diverse marine life.

他们倒栽在河床上，几乎所有人都在坠落中丧生。

They landed upside down on a river ___bed and almost everyone was killed during the fall.

水位下降时，湖底显露出来。

The ___bed of the lake was visible when the water level dropped.