|
Below the twilight layer is the midnight zone(无光层).It is from 600 meters to the bottom of the sea. The water is cold and completely dark.No plants live here but many small animals can. Many animals in the twilight and midnight zones produce their own lights.The angler-fish(琵琶鱼) is one of them.It has a beautiful light on its head to attract prey! Maybe you have seen one of the coolest films Finding Nemo (《海底总动员》).Do you remember Marlin,Nemo’s father,“borrowed” light to help Dory read? That wasn’t a flashlight,it was a fish!They also use light to frighten enemies and to “talk” with each other. 2.Water A family of six needs over 20 gallons of water a day,just for basic drinking,cooking and keeping clean;but only one in three of the world’s households has a water supply in the home. Most others get their water from rivers,lakes springs or holes in the ground,or,in town,from stand-pipes shared with hundreds of other families. Throughout the world’s poorest countries women damage their health and lose hours of every day carrying huge containers of water—up to 44 lbs in weight—often from sources several miles away. All too frequently they bring home sickness or death,as well as water.Untreated water,which may have come from a muddy hole shared with cattle,can be lethal,especially for young children.To sink a well or pipe water from a natural spring,and maintain the system afterwards,people need access to land with a water source,to capital,equipment and technical know-how.In towns they may need to lobby the local water authority to repair or extend existing systems. Water is precious,and access to it gives power—to landowners with wells on their land,or to country controlling major international rivers.The demands on the earth’s water resources are growing rapidly,partly as a result of population growth,but even more because industry now uses such huge quantities—it takes 100 000 gallons to produce a car. (责任编辑：admin) |