on open policy the open policy means that our country is open to investment, trade and technical and economic cooperation with other countries on the basis of equality and mutual benefit. the purpose of open policy is to acquire advanced technology, management skills to serve our socialist construction so as to promote the realization of the four modernizations. human life can not continue without science and technology. for many years, human society has developed with the advance of science and technology while the development of science and technology has in turn brought the process to mankind. so the life we are living now is more civilized than that of our fore fathers. air pollution is one of the major problems of the modern world. a great deal of energy is needed to run the factories of modern industrial nations. automobile, trains, planes and busses need energy, too. nearly all of this energy is produced by burning fuels. the burning produces wastes, some of which remain in the air, causing air pollution. scientists are finding ways to stop air pollution especially in big industrial areas and densely-populated cities. they are studying new ways of generating electricity that may be less damaging to the environment. in the meantime, many power plants are being modernized to give off less polluted material. also, engineers try to design and locate new power plants to do minimum damage to the environment. however, it may be that we still have a long way to go before we have a clean world. nearly all of the countries are trying hard to prevent and control air pollution. there indeed seems to be no end to tasks that environmentalists will be required to do. people will continually find new ways to control pollution.
5. environmental protection concerned people have made some progress in environmental protection. governments of many countries have established laws to protect the air, forests and sea resources and to stop environmental pollution. automobiles, as a product of modern civilization, have been playing a vital part in the daily activities of human society. industry needs automobiles for farming as well as transportation. every day, automobiles drive people to and from work. on weekends automobiles take families for joyful outings. and during holiday seasons, automobiles fill the highways everywhere, even in remote areas. it could be said that the wheels of automobiles move society forward. the main reason why people travel is, perhaps, for pleasure. for e_ample, having worked hard throughout the weekdays, people will find a widened trip to the nearby mountains or beaches a real rela_ation. for another e_ample, spending an annual holiday travelling abroad is an especially satisfying e_perience for those who do not have much of an opportunity to be away from their homelands. when people return from their travel, they will generally feel fresh and energetic, ready to work harder. the human race has e_perienced a consistent increase in population since the beginning of its history. famine and disease have done little to offset(抵消)this steady increase. too many people are added annually to the population of the world. so both the causes of population increase and the results of having more people are worth careful study. culture evolution is the major factor responsible for population increase. early in human development, people invented tools to hunt animals. later they built shelters to protect themselves. step by step, they made life easier. as a result, fewer died from natural forces, such as harsh climate and disease. in the past, when population grew, there was une_plored territory to inhabit. but now, almost all the habitable land has been e_plored. the worlds population may reach 8.7 billion in 2033. it is clear that world population is a serious issue that needs careful attention. human beings are unique to solve problems through cultural evolution.(发展) facing the world population e_plosion in the near future. we must carry out the birth control program in order to save the mankind and save the world.