2013年6月六级真题阅读理解Section B原文+答案解析

　　2013年6月英语六级真题阅读理解Section B原文+答案解析

　　Section B

　　Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A), B), C) and D). You should decide on the best choice and mark the corresponding letter on Sheet 2 with a single line through the center.

　　Passage Two

　　Usually when we walk through the rain forest we hear a soft sound from all the moist leaves and organic debris on the forest floor, says ecologist Daniel Nepstad. Now we increasingly get rustle and crunch. Thats the sound of a dying forest.

　　Predictions of the collapse of the tropical rain forests have been around for years. Yet until recently the worst forecasts were almost exclusively linked to direct human activity, such as clear- cutting and burning for pastures or farms. Left alone, it was assumed, the worlds rain forests would not only flourish but might even rescue us from disaster by absorbing the excess carbon dioxide and other planet-warming greenhouse gases. Now it turns out that may be wishful thinking. Some scientists believe that the rise in carbon levels means that the Amazon and other rain forests in Asia and Africa may go from being assets in the battle against rising temperatures to liabilities. Amazon plants, for instance, hold more than 100 billion metric tons of carbon, equal to 15-years of tailpipe and chimney emissions. If the collapse of the rain forests speeds up dramatically, it could eventually release 3.5-5 billion metric tons of carbon into the atmosphere each year making forests the leading source, of greenhouse gases.

　　Uncommonly severe droughts brought on by global climate change have led to forest-eating wildfires from Australia to Indonesia, but nowhere more acutely than in the Amazon. Some experts say that the rain forest is already at the brink of collapse.

　　Extreme weather and reckless development are plotting against the rain forest in ways that scientists have never seen. Trees need more water as temperatures rise, but the prolonged droughts have robbed them of moisture, making whole forests easily cleared of trees and turned into farmland. The picture worsens with each round of El Nino, the unusually warm currents in the Pacific Ocean that drive up temperatures and invariably presage dead leaves and tree debris make the same sound

　　B) trees that are dying usually give out a soft moan

　　C) organic debris echoes the sounds in a rain forest

　　D) the sound of a forest signifies its health condition

　　58. In the second paragraph, the author challenges the view that _______.

　　A) the collapse of rain forests is caused by direct human interference

　　B) carbon emissions are the leading cause of current global warming

　　C) the condition of rain forests has been rapidly deteriorating

　　D) rain forests should not be converted into pastures or farms

　　59. The author argues that the rising carbon levels in rain forests may _______.

　　A) turn them into a major source of greenhouse gases

　　B) change the weather patterns throughout the world leaves

　　C) pose a threat to wildlife

　　D) accelerate their collapse

　　60. What has made it easier to turn some rain forests into farmland?

　　A) Rapid rise in carbon levels.

　　B) Reckless land development.

　　C) Lack of rainfall resulting from global warming.

　　D) The unusual warm currents in the Pacific Ocean.

　　61. What makes Brazil one of the worlds top five contributors to greenhouse gases?

　　A) The domino effect triggered by the perishing rain forests,

　　B) Its practice of burning forests for settlement and development,

　　C) The changed patterns of winds and rains in the Amazon area.

　　D) Its inability to curb the carbon emissions from industries.