. . -优选 Unit 1 Man has a blood tie with nature and nobody can live outside nature. Nature provides us with everything we need: the air we breathe, the water we drink, and the food we eat. For quite a long time after man began to live in the realm of nature, he lived in fear of its destructive forces. He used to regard nature with its elemental forces as something hostile to him. And even the forest was something wild and frightening to him. Very often, he was unable to obtain the merest daily necessities though he worked together with others stubbornly and collectively with his imperfect tools. Through his interaction with nature, man changed it gradually. He cut down forest, cultivated land, transferred various species of plants and animals to different climatic conditions, changed the shape and climate of his environment and transformed plants and animals. He subdued and disciplined electricity and pelled it to serve the interests of society. . . -优选 Nonetheless, with the constant expansion of agriculture and industry, man has robbed nature too much of its irreplaceable resources, polluted his own living environment and caused about 95% of the species that have existed over the past 600 million years to bee extinct and still many others to be endangered. The previous dynamic balance between man and nature is on the verge of breaking down. Man is now faced with the problem of how to stop, or at least to moderate the destructive effect of technology on nature. The crisis of the ecological situation has bee a global problem. The solution to the problem depends on rational and wise organization both of production itself and care for Mother
