Man is a part of the environment and has done more to upset the ecology during the short span on earth than any other living creature. He had poisoned the atmosphere and polluted both land and water.He has squandered the earth's natural resources with no thought for the future,and has thought out the most devastating ways of killing his fellow men and every other sort of life at the same time. Even at this moment many of the earth's natural treasures are being destroyed, many valuable animals and plants are being killed.Besides,it is becoming increasingly difficult to grow enough food to preserve much of the earth's population from starvation. Man is a part of the environment and has done more to upset the ecology during the short ______ on earth than any other living creature. He had _________ the atmosphere and polluted both land and water. He has ____________ the earth’s natural resources with no thought for the future, and has thought out the most __________ ways of killing his fellow men and every other sort of life at the same time. Even at this moment many of the earth’s natural ____________ are being destroyed, many valuable animals and plants are being killed. Besides, it is becoming increasingly difficult to grow enough food to _______much of the earth’s population from starvation. span poisoned squandered devastating treasures preserve