SeenfromspacetheEarthiscoveredinabluemantle．Itisaplanetonwhichthecontinentsaredwarfed（相形见绌）bytheoceanssurroundingthemandthevastnessofthemarinearea．Anastonishing80percentofallthelifeonEarthisto

　　Seen from space the Earth is covered in a blue mantle．It is a planet on which thecontinents are dwarfed （相形见绌）by the oceans surrounding them and the vastness of the marine area．

　　An astonishing 80percent of all the life on Earth is to be found hidden beneath the waves and this vast global ocean pulses around our world driving the natural forces which keep life on our planet．

　　The oceans provide necessary sources of protein，energy，minerals and other products of use the world over 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 habitable．

　　Without the global ocean there would be no life on Earth．

　　It is seriously worrying，then，that we are damaging the oceans on a scale that is unimagnalbe to most people．

　　We now know that human activity can have serious influences on the vital forces working-on 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 ihe oceans．A healthy ocean has diverse ecosystems and strong and healthy habitats．the actual state of our oceans is a far cry from this natural level．

　　A large quantity of human pressures are being exerted both directly and indirectly on ocean ecosystems the world over．Consequently ecosystems are collapsing as marine speciesare driven towards extinction and ocean habitats are destroyed．With the decrease and removement of their diversity，ocean ecosystems are losing their natural recovery．

　　59．The 2nd and the 3rd paragraphs are given mainly to describe___．

　　A．what the oceans look like

　　B．what the oceans are made up of

　　C．what live in the oceans

　　D．what functions the oceans have