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题库 / Prep2012-RC-43
The sloth bear, an insect-eating animal native to Nepal, exhibits only one behavior that is truly distinct from that of other bear species: the females carry their cubs (at least part-time) until the cubs are about nine months old, even though the cubs can walk on their own at six months. Cub-carrying also occurs among some other myrmecophagous (ant-eating) mammals; therefore, one explanation is that cub-carrying is necessitated by myrmecophagy, since myrmecophagy entails a low metabolic rate and high energy expenditure in walking between food patches. However, although polar bears' locomotion is similarly inefficient, polar bear cubs walk along with their mother. Furthermore, the daily movements of sloth bears and American black bears—which are similar in size to sloth bears and have similar-sized home ranges—reveal similar travel rates and distances, suggesting that if black bear cubs are able to keep up with their mother, so too should sloth bear cubs.
An alternative explanation is defense from predation. Black bear cubs use trees for defense, whereas brown bears and polar bears, which regularly inhabit treeless environments, rely on aggression to protect their cubs. Like brown bears and polar bears (and unlike other myrmecophagous mammals, which are noted for their passivity), sloth bears are easily provoked to aggression. Sloth bears also have relatively large canine teeth, which appear to be more functional for fighting than for foraging. Like brown bears and polar bears, sloth bears may have evolved in an environment with few trees. They are especially attracted to food rich grasslands; although few types of grassland persist today on the Indian subcontinent, this type of habitat was once widespread there. Grasslands support high densities of tigers, which fight and sometimes kill sloth bears; sloth bears also coexist with and have been killed by tree-climbing leopards, and are often confronted and chased by rhinoceroses and elephants, which can topple trees. Collectively these factors probably selected against tree climbing as a defensive strategy for sloth bear cubs. Because sloth bears are smaller than brown and polar bears and are under greater threat from dangerous animals, they may have adopted the extra precaution of carrying their cubs. Although cub carrying may also be adaptive for myrmecophagous foraging, the behavior of sloth bear cubs, which on their mother's back at the first sign of danger, suggests that predation was a key stimulus.
Which of the following, if true, would most weaken the author's argument in the highlighted text?
Cub-carrying behavior has been observed in many non-myrmecophagous mammals.
Many of the largest myrmecophagous mammals do not typically exhibit cub-carrying behavior.
Some sloth bears have home ranges that are smaller in size than the average home ranges of black bears.
The locomotion of black bears is significantly more efficient than the locomotion of sloth bears.
The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.
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正确答案是 B。因为作者认为，在myrmecophagous(食蚁动物)中，母马拉熊要携带幼崽至少9个月是一种独特行为，但B选项表明，许多非myrmecophagous的mammals也会表现出携带幼崽的行为，这削弱了作者的论点。
The locomotion is more efficient的意思是走路更有效率=走同样的距离消耗更少的能源，而不是黑熊走得更快。
C，原文已经说了两种熊的家庭范围差不多，这里some的范围更大，无意义。同时懒熊家庭范围更小，意味着他需要消耗的能量更少，更应该走得动才对。
E，黑熊的栖息地比懒熊的更难走--》那黑熊更走不动才对。
D. The locomotion of black bears is significantly more efficient than the locomotion of sloth bears.（因为black bear行动比sloth bear更efficient，所以black 可以行动了不代表sloth就可以了，可以削弱作者idea）
E. The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.（与题干逻辑方向不符：变成加强，black bear领域更复杂都会自己走了，那么sloth bear领域更简单的，应该也会走了）
原文中已经说了有类似活动范围，这是前提，就不可以反驳。E的话不要脑补黑熊的栖息地一定比懒熊的难走，没这么说。
E是加强！more varied代表地形更复杂。分清楚控制变量的差异是加强还是削弱。
C部分不能否定整体
E 黑熊的栖息地地形比懒熊的更加复杂。然后原文说，"... if black bear cubs are able to keep up with their mother, so too should sloth bear cubs."。这其实是【加强】原文，黑熊在复杂的地形都可以跟上，懒熊在没那么复杂的地形更（也）可以跟上。
rc
不要看到比较就选...感觉好像对就直接选了...有的时候它会故意把比较的方向搞反来误导你
D. The locomotion of black bears is significantly more efficient than the locomotion of sloth bears.（因为black bear行动比sloth bear更efficient，所以black 可以行动了不代表sloth就可以了，可以削弱作者idea）
E. The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.（与题干逻辑方向不符：变成加强，black bear领域更复杂都会自己走了，那么sloth bear领域更简单的，应该也会走了）
类比推理，说这俩熊体型和生活半径都相似，所以孩子都能跟着妈妈走。只要举出反例，他俩不一样的地方。剩下D和E E说黑熊生活的地形更多样，那么就是懒熊生活的平坦，感觉懒熊的孩子更容易出来走走。。。
D的关键在efficient
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E. The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.（与题干逻辑方向不符：变成加强，black bear领域更复杂都会自己走了，那么sloth bear领域更简单的，应该也会走了）
这个题，真的，一开始没看出来d对，但是12肯定不对，3，5也排除了，这个题。。。说难不难，说简单不简单，就是别扭
这个题，真的，一开始没看出来d对，但是12肯定不对，4，5也排除了，这个题。。。说难不难，说简单不简单，就是别扭。
因为black bear和sloth bear有着相似的1）size 2）home ranges -> 如果黑熊幼崽可以自己走路，那么sloth bear的幼崽也可以。问削弱
choice d, black bear的locomotion比起sloth bear的更加有效
不要不仔细看选项...感觉好像对就直接选了...有的时候它会故意把比较的方向搞反来误导你
E.black bear的活动地的地形比sloth bear更复杂=》那就说明sloth更应该能把娃放下来啊！！人家black bear的地形比你复杂都能把娃放下来
E选项说，黑熊的栖息地地形比懒熊的更加复杂。然后原文说，如果黑熊可以跟上，那么懒熊也可以跟上。这其实是加强了原文，他在复杂的地形都可以跟上，懒熊在没那么复杂的地形更（也）可以跟上。
这道题好狡猾哦
①先提到一个A低代谢高消耗的问题，然后说有一种熊也有这样的特点，但是它就和sloth在cub不一样
②又提到B体型的问题，说有几种熊和sloth如何如何一样，但是它就和sloth 在cub方面不一样
然后题目问你如何削弱②好推论：那你这几种熊和sloth在B方面一样，你能保证他们在A方面也是一样的嘛？逻辑题里的错误类比
找结论
Furthermore, the daily movements of sloth bears and American black bears—which are similar in size to sloth bears and have similar-sized home ranges—reveal similar travel rates and distances, suggesting that if black bear cubs are able to keep up with their mother, so too should sloth bear cubs.
文章提到了range, 也提到了travel rate(locomotion)
travel rate 是直接结论。
D. The locomotion of black bears is significantly more efficient than the locomotion of sloth bears.（因为black bear行动比sloth bear更efficient，所以black 可以行动了不代表sloth就可以了，可以削弱作者idea）
E. The habitat of black bears consists of terrain that is significantly more varied than that of the habitat of sloth bears.（与题干逻辑方向不符：变成加强，black bear领域更复杂都会自己走了，那么sloth bear领域更简单的，应该也会走了）
E为啥不对呢