请教GWD-29-Q9

青色石头

GWD-29-Q9
Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats.  To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds.  Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows.  Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?

A.    The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported collisions between manatees and boats.
B.    Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat traffic.
C.    Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the endangered manatee population.
D.    The sound of a boat engine generally travels much further under water than it does through the air.
E.    When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal background noise.

答案是E，我选的是D，并且还想了半天不明白，请高人帮忙敲打一下，多谢

newconcept123

大多数人都认为 worse取反就是better 其实还有一种可能就是neutralize;就像负数取反是零和正数一样。
这道题目就是用这样一个概念。

amy520143

b选项说的是食物现在不被声音干扰，海牛听不到声音来吃，撞船了。所以情况更糟了。所以是肯定结论。
但是原文问的是cast doubt on the conclusion。 所以b 正好是反的选项。
ron有解释。

liyao604

zongheimun 发表于 2011-7-21 01:42
B项说法加入了其他因素（即开慢船有利于保护海牛的食物），但如果原题中的原因依旧成立（即开慢船有可能使 ...

棒！就是这样。GMAT经常用这种选项混淆视听。这种选项的错误就是没有办法衡量结果到底是利大于弊还是弊大于利

rogel_wang

我也一直纠结为什么答案是E而不是B.
我又仔细读了几遍题目，然后想通了。
题目上来先讲了现在的状况，也就是问题。Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats.  这是一个显示了因果关系的fact. 我们在削弱结论时是不能靠削弱这个fact来成立。
然后又说就算船放慢了速度，因为海牛听不到低振幅的声音，所以情况（问题）可能不会改善而且可能会撞死更多的海牛。问削弱。
而E说实验证明海牛根本无法分辨声音的强弱，可以推出慢船没有使情况变得更糟。加上第一句话的那个fact,表明可以改善现在的状况。即船速度的快慢可以改变海牛的数量，不是因为海牛是否听得到，而是因为速度慢比速度快更少撞到海牛。

rachelbaby321

B虽然保护了食物还是由于听不见造成了事故，那么这个方法还是worse，不能削弱

花露水6

啊 一语惊醒梦中人呢

super0119

做题时刚刚看到B就选了而忽略看E了

biabia123

同意17L的
如果M听不见，直接会造成更多的死亡，即使吃的东西被保护起来了，但是死都死了还怎么吃。。。

克克里斯蒂

小女子浅见。
选B
此题结论是Therefore, this approach may in fact make things worse rather than better. 要反驳就要说this approach是好的，不会make things worse. this approach是指boat traffic in manatee-populated waters is being required to maintain very low speeds，也就是船要慢开。我们要选的答案应该是说船应该慢开。
A 说选地方的，无关
B 正答。M这动物的食物是h，这个h需要安静，快船会打扰甚至破坏h, 那h都破坏了，m就饿死了呀，所以要开慢船。
C 增长及现状，无关
D 这个很混淆视听，但是还是错的。因为题目中说M unable to hear low-pitched sounds，与声音传的远近无关的。
E M接触各种速度后，我们发现他们不能分辨出声音和背景，那么快船，慢船就无所谓了。

请各位大师评鉴。

-- by 会员 luckysw (2011/10/9 21:33:41)

我觉得
E并非快船、慢船无所谓，只是在Manatees是否能辨认船靠近的声音上没有差别，因为都辨别不出。但是考虑到原文暗示速度慢了就比较少发生碰撞事件了，所以根据E可以得出的结论是this approach make things better. 正确选项
至于B我一开始也错选了，后来发现原文中指出To address the problem, 也就是指着Manatees killed in collisions with boats说的，原文的结论是Therefore, this approach may in fact make things worse rather than better. 我觉得也是应该指着collsions说的，Manatees的食物什么状况是跟collision没有关系的。所以是无关选项。