2017-08-12 436阅读
以下将为正在备战GMAT考试的同学们整理一些经典的GMAT阅读试题,并分多个合集推出,希望能够为正在备考GMAT考试的考生提供或多或少的帮助。
Over the last 150 years, large
stretches of salmon habitat have
been eliminated by human activity:
Line mining, livestock grazing, timber
(5) harvesting, and agriculture as well
as recreational and urban devel-
opment. The numerical fect is
obvious: there are fewer salmon
in degraded regions than in pris-
(10) tine ones; however, habitat loss
also has the potential to reduce
genetic diversity. This is most
evident in cases where it results
in the extinction of entire salmon
(15)populations. Indeed, most
analysts believe that some kind
of environmental degradation
underlies the demise of many
extinct salmon populations.
(20)Although some rivers have
been recolonized, the unique
genes of the original populations
have been lost. 提出现象:数量减少,基因多样性下降,因为环境问题
Large-scale disturbances in
(25)one locale also have the potential
to alter the genetic structure of
populations in neighboring areas,
even if those areas have pristine
habitats. Why? Although the
(30)homing instinct of salmon to their
natal stream is strong, a fraction
of the fish returning from the sea
(rarely more than 15 percent)
stray and spawn in nearby
(35) streams. Low levels of straying
are crucial, since the process
provides a source of novel
genes and a mechanism
by which a location can be
(40)repopulated should the fish
there disappear. Yet high rates
of straying can be problematic
because misdirected fish may
interbreed with the existing stock
(45)to such a degree that any local
adaptations that are present
become diluted. Straying
rates remain relatively low when
environmental conditions are
(50)stable, but can increase dramati-
cally when streams suffer severe
disturbance. The 1980 volcanic
eruption of Mount Saint Helens,
for example, sent mud and debris
(55)into several tributaries of the
Columbia River. For the next
couple of years, steelhead trout
(a species included among the
salmonids) returning from the
(60)sea to spawn were forced to
find alternative streams. As
a consequence, their rates of
straying, initially 16 percent,
rose to more than 40 percent
(65)overall.另外后果及原因:干扰同样导致基因结构变化,因为洄游路线频率上升
Although no one has quantified
changes in the rate of straying
as a result of the disturbances
caused by humans, there is no
(75) matic increase in straying from
damaged areas to more pristine
streams results in substantial
gene flow, which can in turn lower
the overall fitness of subsequent
generations.最终结果:后代适应性变差
结论解释
逻辑简图:
1P:samlon habitat eliminated by… fect obvious: fewer; however, reduce genetic diversity
2P: also alter genetic structure. Low crucial; yet high, problematic.
3P: although, no reason to suspect…. Increase result in, in turn lower the …..
相关链接:
1.浅析GMAT阅读的提升技巧
2.GMAT备考经验分享:不要忽视阅读和逻辑(一)
3.GMAT阅读解题技巧:抽象词速度法
想要获得更多咨询服务点击进入 >>>>有问题?找免费的澳际专家咨询! 或联系QQ客服: ,也可以通过在线咨询处留言,把您最关心的问题告诉我们。
Copyright 2000 - 2020 北京澳际教育咨询有限公司
www.aoji.cn All Rights Reserved | 京ICP证050284号
总部地址:北京市东城区 灯市口大街33号 国中商业大厦2-3层
高国强 向我咨询
行业年龄 11年
成功案例 2937人
留学关乎到一个家庭的期望以及一个学生的未来,作为一名留学规划导师,我一直坚信最基本且最重要的品质是认真负责的态度。基于对学生和家长认真负责的原则,结合丰富的申请经验,更有效地帮助学生清晰未来发展方向,顺利进入理想院校。
Tara 向我咨询
行业年龄 6年
成功案例 1602人
薛占秋 向我咨询
行业年龄 10年
成功案例 1869人
从业3年来成功协助数百同学拿到英、美、加、澳等各国学习签证,递签成功率90%以上,大大超过同业平均水平。
Cindy 向我咨询
行业年龄 18年
成功案例 4806人
精通各类升学,转学,墨尔本的公立私立初高中,小学,高中升大学的申请流程及入学要求。本科升学研究生,转如入其他学校等服务。