21.  The brackish water becomes trapped beneath the surface with no place to go.

22.  The researchers said this is important, because the longer stubble traps more water.

23.  The workers earn their living by erecting sand walls to trap sea water, and collecting salt for sale after the water evaporates.

24.  Torrential summer rains are often accompanied by deadly flooding because centuries of overfarming have stripped hills of vegetation that would trap rain water.

25.  Torrential summer rains in southern China are accompanied by deadly flooding because centuries of overfarming have stripped hills of vegetation that would trap rain water.