carving2013年6月英语六级阅读理解Setion B2原文答案及点评(沪江网校版)

2021年1月20日发(作者：火电站)
2013
年
6
月英语六级阅读理解
Setion B2
原文答案及点评（沪江网校版）

2013
年
6
月英语六级考试阅读理解
Section B2
原文答案及点评，由沪江
网校提供。考完试的同学可以对比一下，备考的同学也可以研究一下考题。< br>希望大家六级考试顺利通过。

Part IV Reading Comprehension

Section B-2
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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

“Usu
ally 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. That’s 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
world’s 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 (
预示）
droughts
and fires in the rain forest. Runaway fires pour even more carbon
into the air, which increases temperatures, starting the whole
vicious cycle all over again.
More than paradise lost, a perishing rain forest could trigger a
domino effect sending winds and rains kilometers off course and
loading the skies with even greater levels of greenhouse
gases
—
that will be felt far beyond the Amazon basin. In a sense,
we are already getting a glimpse of what’s to come. Each burning
season in the Amazon, fires deliberately set by frontier settlers and
developers hurl up almost half a billion metric tons of carbon a year,