2017届高考英语三轮冲刺复习：完形与阅读强化训练21_高考复习指南

2017届高考英语三轮冲刺复习：完形与阅读强化训练21

　　Seen from space the earth is covered with a blue mantle. It is a planet on which the continents are dwarfed (相形见绌) by the ocean surrounding them and the vastness of the marine (海洋的) area.

　　An astonishing 80 percent of all life on earth is to be found hidden beneath the waves and this vast global ocean drives the natural forces which keep life on our planet. The ocean provides necessary sources of protein, energy, minerals and other products and the rolling of the sea across the planet creates over half our oxygen, drives weather systems and natural flows of energy and nutrients around the world, transports water masses many times greater than all the rivers on land combined and keeps the earth suitable for living things to survive. Without the global ocean there would be no life on earth.

　　It is seriously worrying, then, that we are damaging the ocean on a level that is unimaginable to most people.

　　We now know that human activity can have a serious influence on the vital forces of our planet. We have fundamentally changed our global climate and are just beginning to understand the consequences of that.

　　As yet largely unseen, but just as serious, are the influences we are having on the ocean. A healthy ocean has diverse ecosystems and strong and healthy habitats. The actual state of our ocean is a far cry from this natural state.

　　A lot of pressure is being put directly and indirectly on ocean ecosystems by human activities. Consequently ecosystems are breaking down as marine species are in danger of dying out and ocean habitats are being destroyed. With the decrease in their diversity, ocean ecosystems are losing their natural way of recovery.