保护地球英语作文100字七年级 The area of desert in the world is growing every year. Many parts of the world which once had large populations and produced plenty of crops, have become deserts. Dunhuang in China, deep in the heart of the Gebi Desert, was once a great city. Cattle are one cause of the problem. In good years, famers increase the numbers of their cattle. Then one year, the rains fail to come. The farmers do not want to kill any of their cattle, so the cattle eat ail the grass and anything that grows on poorer land. If this continues for several years, the grass never grows again and the land becomes a desert. One suggested answer is for farmers to limit the numbers of their cattle. Another problem is that good soil is gradually lost. When trees are cut down, there is nothing to hold the soil in place on the hillside. So when if rains, the soil is washed down the hills and into the rivers. Strong winds can also blow away the valuable soil that lies on the top of the fields. Throughout history man has changed his physical environment in order to improve his way of life. With the tools of technology he has altered many physical features of the earth. He has transformed woodlands and prairies into farms and made lakes and reserviors out of rivers for irrigation purposes or hydroelectric power. Man has also modified the face of the earth by draining marshes and cutting through mountains to build roads and railways. However, man's changes to the physical environment have not always had beneficial results. Today, pollution of the air and water is an increasing danger to the health of the planet. Each day thousands of tons of gases come out of the exhausts of motor vehicles. Smoke from factories pollutes the air of industrialized areas and the surrounding areas of the countryside. The pollution of water is equally harmful. The whole ecological balance of the sea is being changed and industrial wastes have already made many rivers lifeless. Now environmental protection is more pressing than ever before. As we know, massive destruction of environment has brought about negative effects and even poses a great threat to man's existence. Indifference to these problems will mean committing suicide. Therefore, effective measures should be taken and laws passed to conserve environment. Otherwise,man is certain to suffer from the serious consequences caused by this lack of care for his living surroundings. Too many cars have created a lot of serious problems in our world. Besides congestion, accidents and fast fuel consumption, cars are responsible for a good part of air pollution in big cities. All the time, they are pumping huge amounts of waste gases into the atmosphere. These gases are very harmful, causing disease and even death. One possible solution is to design and develop clean cars and clean fuels. In Shanghai, some of the public buses begin to run on natural gas, which does not give off as much carbon dioxide as the petrol. But it may take decades for the new models of clean cars completely replace the traditional ones. Another solution is to develop modern public transportation systems and restrict the use of private cars. If the price of petrol rises constantly and the public vehicles are efficient and convenient enough, most people will not buy private cars. And the total number of cars in big cities will reduce greatly. On the whole, the elimination of air pollution needs the collective efforts from the government, the public and the environmentalists. 感谢您的阅读，祝您生活愉快。 本文来源：https://www.wddqw.com/doc/bb478d86e65c3b3567ec102de2bd960590c6d9a5.html