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题库 / GMATAdvanced-CR-40
First discovered several years ago in North American lakes and rivers, the northern snakehead is a nonnative fish with no local predators. To keep the northern snakehead ’s population from growing, for the past three years wildlife officials have been paying recreational fishers for each northern snakehead they catch. In this way, the officials hope to stop the northern snakeheads from eliminating rare native fish species.
To evaluate the likelihood that the wildlife officials’ plan will succeed, it would be most useful to determine which of the following?
Whether the northern snakehead’s population in local lakes and rivers could be reduced by introducing predators from its native habitat
How local population numbers of rare native fish species have been changing since the wildlife officials started paying recreational fishers to catch northern snakeheads
Whether the fish species on which the northern snakehead preys in regions to which it is native and in which it is abundant have become significantly depleted in recent decades
What total number of northern snakehead have been caught by recreational fishers since the wildlife officials began paying for them
Whether rare native fish species in the region face any threats to their survival other than the proliferation of northern snakehead
D，单知道被抓的鱼的数量不知道被抓的鱼的数量占总量的比例也是没有滴，比如抓了1万条，但是总共可能有1亿条，杯水车薪，该被鱼吃光的还是会被吃光。
B，stop sb from doing sth阻止某人做某事，可以看成是已经做了，现在要他stop，说明黑鱼的存在已经威胁到了稀有的当地鱼的数量，所以黑鱼如果少了，稀有鱼的数量就会上升，而不是因为是稀有鱼，所以数量该稀少还是稀少。
目标：stop the northern snakeheads from eliminating rare native fish species. --让ns无法抓稀有鱼
方案： paying recreational fishers for each northern snakehead they catch.-- 让fisher来catch ns，从而控制ns的数量
然后就可以发现ns减少了和让ns无法抓稀有鱼之间有个gap，【fisher抓ns】 和 【ns抓稀有鱼】 之间没有建立联系
B：fisher抓ns和稀有鱼减少之间有联系，正好弥补了这个gap。这是一道典型的搭桥假设题。
B：How local population numbers of 【rare native fish species】 have been changing since the wildlife officials started 【paying recreational fishers】 to 【catch northern snakeheads】。（最相关）
自从野生动物官员开始【付钱给休闲渔民】去【捕捉北方蛇头】后，当地【珍稀本土鱼类】的种群数量发生了怎样的变化
E没有讲pay fisher
找到conclusion 衡量是否能完成最终的目的最重要
目的是S不要再消灭R了，最需要知道的应该是在fisher引进之后R有没有什么变化
目的是S不要再消灭R了，最需要知道的应该是在fisher引进之后R有没有什么变化
目的只有一个：让S不要再影响R的数量，错选了E，E脱离了S的关系，所以不对。B最直接
B can directly illustrate the issue.
the wildlife officials的目的是通过keep the northern snakehead ’s population from growing来stop the northern snakeheads from eliminating rare native fish species，而目的并非单纯保护rare native fish species
减少数目的目的是stop the northern snakeheads from eliminating rare native fish species.
D项：渔民如果专门养这种鱼去拿赏金。。。
Best answer: most related fact
为啥这题有两个目的：1是让这种鱼的数量不要增长了；2是让这种鱼不要再减少珍稀鱼了...
政府希望藉由減少snakehead的數量來達成「遏止snakehead殘害當地珍稀魚」的目的，因此最終目標只有一個。
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To determine whether it is responsible to keep paying these fishers to catch northern snakehead, it is vital to understand whether the fishers' work up to this point has had any observable effect.
E. Determining whether there are other threats to the rare native fish species would tell us whether the plan, if successful, is sufficient to save the rare fish species. Still, it is not useful in determining whether that plan is likely to be successful.