（21）Depleting the ozone layer allows more UV-B to reach the earth, which means more skin cancers, more eye cataracts（白内障），weakened immune systems, and reduced plant yield.
（22）The nature has been irritated, which results in the shortage of valuable resources, air pollution, countless acres of lands becoming deserts, etc.
（23）Fortunately, many countries have got to know the seriousness of the problem and take active measures to preserve the environment.
（24）We sincerely hope that all the people in the world will take part in the campaign and join hands to protect the nature.
（25）Besides, trees and lawns in our cities will in the long run help improve the local climate.
（26）The government should also spend more money on the preservation of current lawns and cultivation of new lawns.
（27）Chinese government has taken strict measures to stop careless and indiscriminate felling of trees.
 
（28）Therefore, governments are playing the most important role in environmental protection today.
（29）The government should let people full realize the importance of environmental protection through education.
（30）Cars should be equipped with special devices to reduce auto emission.
（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.