（31）Farmers can utilize modern biological techniques instead of chemical fertilizers to grow crops.
（32）Desert can be turned into cultivated land by a certain kind of shrub.
（33）Recycling of paper, steel and plastics is important for helping protect our environment.
（34）The city was beautified on a tremendous scale.
（35）Energy crisis will threaten our existence because of the people’s extravagance and the rapid growth of he population.
（36）It is imperative that we investigate and develop new sources of energy immediately.
（37）With the expansion of industrialization, requirement for energy all over the world is on the rise.
（38）We have a great need for energy because of the rapid growth of our economy.
（39）These rich energy resources are being used up rapidly.
（40）To avoid energy crisis in the future, we should take some actions.
（41）The overuse of energy has influenced ecological balance.
（42）The development of modern life is placing and ever increasing demand for electricity.
（43）If there were no energy, our world would be in a state of confusion.
（44）Protecting endangered species helps protect a healthy environment. Endangered species are nature’s early warning system for pollution and environmental degradation that may someday affect human health.（濒危物种是大自然的关于污染和环境恶化的早期警戒系统，污染和环境恶化有朝一日会影响人类的健康。）
（45）Protecting endangered species saves a part of nature for our children and grandchildren to enjoy.
（46）Protecting endangered species helps protect sustainable economies and a good quality of life. Endangered species of fish, wildlife and plants are of ecological, educational, historical, recreational and scientific value to the nations and their people.
（47）All of the living creatures, including humans, are part of a complex, delicately balanced network called the biosphere.
（48）No creature exists in isolation. The removal of a single species can set off a chain reaction affecting many others.
（49）It is estimated that about 12,000 Tibetan antelopes are killed each year. If this trend continues, this species will be extinct in two decades.
（50）A healthy environment for wildlife contributes to healthy environment for people, today and tomorrow.