Passage FourThe atmosphere and oceans are not the only parts of the environment being damaged. Rain forests are being quickly destroyed as well, and their survival is questionable. E. O. Wilson, a biologist at Harvard, calls the depletion(枯竭、耗尽)of rain forest areas "the greatest extinction since the end of the age of dinosaurs(恐龙)."Unlike some environmental issues, rain forests' depletion has fortunately received significant public and media's attention. Despite the opposition to the cutting down of rain forests, the problem continues. Every year, Brazil chops down an area of forests the size of the state of Nebraska. In addition to the Amazon's rain forests, many other forests are being cut down as well.: In Indonesia, Zaire, Papua-new Guinea, Malaysia, Burme, the Philippines, Peru, Colombia, Bolivia, and Venezuela, rain forests that were once great have been lost.According to some estimates, 50 million acres of rain forest are cut down every year. The United Nations says the figure is closer to 17 million acres. The World Wildlife Fund says that every minute,25 to 50 acres are cut down or burnt to the ground.The world's growing population has been a primary reason of rain forests' destruction. More people need land to live on and wood products to consume. Limiting population growth may be the first in a series of steps that would alleviate the destruction of the rain forests.48. In the opinion of the author, ______are being destroyed terribly at present.