-
阅读原文：
The deserts, which already occupy
approximately a fourth of the Earth's land
surface, have in recent decades been
increasing at an alarming pace. The expansion
of desertlike conditions into areas
where they did not previously exist is called
desertification.
It
has
been
estimated
that
an
additional
one-fourth
of
the
Earth's
land surface is threatened by this
process.
沙漠已经占据了地球陆地面积约四分之一
，而且最近几十年正以惊人的速度扩张。沙漠
化是指类似沙漠的环境漫延到原本并非沙漠
的区域。据估计，地球表面另外四分之一的地方
正面临沙漠化威胁。
Desertification
is
accomplished
primarily
through
the
loss
of
stabilizing
natural
vegetation and the subsequent accelerated erosion
of the soil by wind and
water.
In
some
cases
the
loose
soil
is
blown
completely
away,
leaving
a
stony
surface.
In other cases, the
finer particles may be removed, while the sand-
sized particles
are accumulated to form
mobile hills or ridges of sand.
沙漠化主要通过以下过程实现：首先自然植被不断减少，随后风力和雨水加速了土壤的
腐蚀。有的时候松散的土壤全部被风刮走，留下石质化的表层；其它情况下细小的沙粒可能
会被吹走，而正常沙粒大小的砂子不断堆积，从而形成移动的沙丘或者沙脊。
Even
in
the
areas
that
retain
a
soil
cover,
the
reduction
of
vegetation
typically
results
in
the
loss
of
the
soil's
ability
to
absorb
substantial
quantities
of
water.
The
impact
of
raindrops
on
the
loose
soil
tends
to
transfer
fine
clay
particles
into
the
tiniest
soil
spaces,
sealing
them
and
producing
a
surface
that
allows
very
little
water penetration.
Water absorption is greatly reduced; consequently
runoff is
increased, resulting in
accelerated erosion rates. The gradual drying of
the soil
caused by its diminished
ability to absorb water results in the further
loss of
vegetation, so that a cycle of
progressive surface deterioration is established.
即便是在保留了土壤表层的区域，植被减少也已成为土壤大量
吸取地下水的能力下降的
典型因素。
雨水对松散土壤的冲击会把
细小的粘土颗粒冲到土壤空隙中，
封闭
了土壤并降低
土地表层水的渗透率。地表对水的吸收急剧减少，大量水资源流失，因此
土壤的腐蚀率也随
即增加。
地表吸收水分的能力进一步弱化使得
土壤越发干
燥，
导致植被的进一步流
失，
于是
便形成了土壤沙漠化的恶性循环。
In
some
regions,
the
increase
in
desert
areas
is
occurring
largely
as
the
result
of a trend toward drier climatic
conditions. Continued gradual global warming has
produced
an
increase
in
aridity
for
some
areas
over
the
past
few
thousand
years.
The
process may be accelerated in
subsequent decades if global warming resulting
from
air pollution seriously increases.
在一些
地方，沙漠面积的扩大很大程度上归因于干燥的气候条件。在过去的几千年里，
不断增加
的温室效应使得一些地方干旱问题愈发严重。倘若空气污染带来的温室效应继续恶
化，沙
漠化进程会在未来数十年内加速实现。
There is little doubt, however, that
desertification in most areas results
primarily from human activities rather
than natural processes. The semiarid lands
bordering
the
deserts
exist
in
a
delicate
ecological
balance
and
are
limited
in
their
potential
to
adjust
to
increased
environmental
pressures.
Expanding
populations
are
subjecting the land to increasing
pressures to provide them with food and fuel. In
wet
periods,
the
land
may
be
able
to
respond
to
these
stresses.
During
the
dry
periods
that
are
common
phenomena
along
the
desert
margins,
though,
the
pressure
on
the
land
is often
far in excess of its diminished capacity, and
desertification results.
然而
，可以肯定的是，大部分地区沙漠化主要都是由于人类活动造成，而非自然条件导
致。<
/p>
沙漠边缘的半干旱土地所处的生态平衡环境非常脆弱，
环境压力持
续增
加，
而这些半干
旱区域适应环境压力的能力极其有限。人口数量的增加使得人们不断向土地施压，依其提供
食物和燃料。
在湿润的季节里，
土地兴许能够应付这
些压
力。
但是在干旱的季节里，
在沙漠
周边的土地上，存在着这样一个十分普遍的现象：人类对土地
施加的压力远远超过了土地自
身减压的能力，因此最终形成了沙漠。
Four specific activities
have been identified as major contributors to the
desertification processes:
overcultivation, overgrazing, firewood gathering,
and
overirrigation. The cultivation of
crops has expanded into progressively drier
regions as population densities have
grown. These regions are especially likely to
have
periods
of
severe dryness, so that crop failures are common.
Since
the raising
of
most
crops
necessitates
the
prior
removal
of
the
natural
vegetation,
crop
failures
leave extensive
tracts of land devoid of a plant cover and
susceptible to wind and
water erosion.
导致沙漠化的主要因素有四个：过度种植，过度放牧，过分砍
伐，过度灌溉。由于人口
密度增加，
人们对粮食作物的种植已经
扩展到日益干燥的区域进行。
这些区域
很有可能经常
会发生干旱，所以农作物种植失败是很正常的事情。大多数农作物的种植
需要事先移除天然
植被，而农作物欠收后又会留下大面积荒地，非常容易被风
力和雨水侵蚀。
The raising of livestock is a major
economic activity in semiarid lands, where
grasses are generally the dominant type
of natural vegetation. The consequences of
an
excessive
number
of
livestock
grazing
in
an
area
are
the
reduction
of
the
vegetation
cover and the trampling and
pulverization of the soil. This is usually
followed by
the drying of the soil and
accelerated erosion.
在半干旱地区
，草坪是主要的天然植被，家畜饲养是当地的一项主要经济活动。在一个
地区过量饲养家
畜会导致植被覆盖面积减少，土地被大量践踏和碾碎。通常，随之而来的就
是土地硬化和
加速侵蚀。
Firewood is the chief fuel
used for cooking and heating in many countries.
The
increased
pressures
of
expanding
populations
have
led
to
the
removal
of
woody
plants
so that many cities
and towns are surrounded by large areas completely
lacking in
trees and shrubs. The
increasing use of dried animal waste as a
substitute fuel has
also hurt
the
soil
because
this
valuable
soil
conditioner
and
source
of
plant
nutrients is no longer being returned
to the land.
在很多国家木材是用来做饭和加
热的最主要燃料。人口增加带来的压力促使人们大量砍
伐木材，导致许多城市和乡村周围
大面积树木和灌木减少。同时人们大量使用烘干的动物排
泄物作为替代燃料同样对土壤不
利，因为这些珍贵的土壤成分调节剂和植物营养资源将不会
再回归至土壤当中。
The final major
human cause of desertification is soil
salinization resulting
from
overirrigation. Excess water from irrigation sinks
down into the water table.
If
no
drainage
system
exists,
the
water
table
rises,
bringing
dissolved
salts
to
the
surface.
The
water
evaporates
and
the
salts
are
left
behind,
creating
a
white
crustal
layer that prevents
air and water from reaching the underlying soil.
造成土地沙漠化的最后一个主要人为因素在于人类过度灌溉导
致土壤的盐碱化。灌溉多
余的水渗透到地下水位。假如没有排水系统的存在，那么地下水
位上升，把溶解的盐分带到
土壤表面。水分蒸发后，盐分留在了表面，形成白色的地壳层
，这一地壳层阻止了空气和水
接触地底下的土壤。
The extreme seriousness of
desertification results from the vast areas of
land
and the tremendous numbers of
people
affected, as well as from the
great difficulty
of
reversing
or
even
slowing
the
process.
Once
the
soil
has
been
removed
by
erosion,
only the passage of
centuries or millennia will enable new soil to
form. In areas
where
considerable
soil
still
remains,
though,
a
rigorously
enforced
program
of
land
protection and cover-crop planting may
make it possible to reverse the present
deterioration of the surface.
沙漠化问题异常严重，这是因为有佷广阔的地区和数量庞大的
人群都受到了沙漠化的影
响，
而且要想逆转沙漠化的进程甚至减
缓沙漠化的速度都面临着巨大的困难。
一旦土壤被侵
蚀，需要再经过几百到上千年的时间才会产生新的土壤。那些大量土壤仍保存完好的地方，
亟需一个严谨而有力的保护政策和植被覆盖计划来保护现有
土地。
第
1
题：
The word threatened in the
passage is closest in meaning to
A
：
Restricted
B
：
Endangered
C
：
Prevented
D
：
Rejected
解析：
threatened
受到威胁的，
很容易选出
B
选项，
endanger
ed,
使危险。
依据上下文，
前句<
/p>
说什么是
desertification,
< br>本句说还有
1
／
4
的土地被这种过程（沙漠化）如何，也很容易
猜出选项。
第
2
题：
According
to
paragraph
3,
the
loss of natural
vegetation
has which
of
the
following consequences for soil?
A
：
Increased stony
content
B
：
Reduced water
absorption
C
：
Increased
numbers of spaces in the soil
D
：
Reduced water
runoff
解析：
This
is
a
Factual
Information
question
asking
for
specific
information
that
can
be found
in paragraph 3. The
correct
answer is choice 2, reduced water absorption. The
paragraph explicitly
states that the
reduction of
vegetation
greatly reduces water absorption. Choice 4,
reduced water runoff,
explicitly
contradicts the
paragraph,
so
it
is
incorrect.
The
in
the
soil
are
mentioned
in
another
context: the paragraph does
not say that they increase, so choice 3
is incorrect. The paragraph does not
mention choice
第
3
题：
The
word delicate in the passage is closest in meaning
to
A
：
Fragile
B
：
Predictable
C
：
Complex
D
：
Valuable
解析：
This
is
a
Vocabulary
question.
The
word
being
tested
is
delicate.
It
is
highlighted in the passage. The correct
answer is choice 1,
meaning as
第
4
题：
According to paragraph 5,
in dry periods, border areas have difficulty
A
：
Adjusting to
stresses created by settlement
B
：
Retaining their
fertility after desertification
C
：
Providing water
for irrigating crops
D
：
Attracting
populations in search of food and fuel
解析：
根据
dry period
定位本段
末句，说在沙漠边缘典型的干旱期，对土地的压力经常远远
超过土读弱化的能力，从而导
致沙漠化。并且前句说，在湿润季节，土地或许能回应这些压
力。前后对比可知干旱期不
能回应这些压力。
A
正确，本句和前句内容概括。
B
错，沙漠化之后的结果没有提到。
C
错，没有提到。
D
错，没有提到。
第
5
题：
The word progressively in
the passage is closest in meaning to
A
：
Openly
B
：
Impressively
C
：
Objectively
D
：
Increasingly
解析：
progressively,
由词跟
gress
走和前缀
pro
向前可知
词义大致是进步的，
前进的，
增加
的。
D
正确。
A
公开的，
B
印象深刻的，
C
客观的都不对。
第
6
题：
According
to
paragraph
6,
which
of
the
following
is
often
associated
with
raising
crops?
A
：
Lack of proper
irrigation techniques
B
：
Failure to
plant crops suited to the particular area
C
：
Removal of the
original vegetation
D
：
Excessive use
of dried animal waste
解析：
This
is
a
Factual
Information
question
asking
for
specific
information
that
can
be found in paragraph 6.
The
correct
answer
is
choice
3,
of
the
original
vegetation.
Sentence
4
of
this
paragraph says that
raising
of
most
crops
necessitates
the
prior
removal
of
the
natural
vegetation,