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题库 / GMATLA-CR-99
Plankton generally thrive in areas of the ocean with sufficient concentrations of certain nitrogen compounds near the surface, where plankton live. Nevertheless, some areas, though rich in these nitrogen compounds, have few plankton. These areas have particularly low concentrations of iron, and oceanographers hypothesize that this shortage of iron prevents plankton from thriving. However, an experimental release of iron compounds into one such area failed to produce a thriving plankton population, even though local iron concentrations increased immediately.
Which of the following, if true, argues most strongly against concluding, on the basis of the information above, that the oceanographers' hypothesis is false?
Not all of the nitrogen compounds that are sometimes found in relatively high concentrations in the oceans are nutrients for plankton.
Certain areas of the ocean support an abundance of plankton despite having particularly low concentrations of iron.
The release of the iron compounds did not increase the supply of nitrogen compounds in the area.
A few days after the iron compounds were released, ocean currents displaced the iron-rich water from the surface.
The iron compounds released into the area occur naturally in areas of the ocean where plankton thrive.
这个讲的是 以下哪个选项 反驳了 在当前信息基础下，给出结论说假设是错误的这个论断。
-----这个问题不是在暗示学者的假设是对的，而是要反驳 仅仅凭借当前实验结果，不能够得出iron无关plankton population 的结论。
简而言之，就是找出一个说明实验或者实验结果有问题的选项，D正确，因为iron很快就被冲走了，所以iron根本没有聚集，这个实验失败了，依据这个实验给出的结论自然是ungrounded
题目的immediately其实是个信号词，对应了D的few days later. 几天后iron的那些物质就飘走了，那么添加的iron对浮游生物就没什么影响
因果：
理想结果 release of iron compounds into one such area ➡️ produce a thriving plankton population 而实验中没做到 所以考虑实验中的其他变量
如果符合正常假设结果，那就是加入Iron，此时水域Iron含量高，Plankron数量也会多，但是实际没有，否定了假设。但是相反，如果此时Iron含量低，那Plankron的数量也少的话就能解释假设了。那么就得寻找加入Iron后，它含量还低的其他原因了登录 或 注册 后可以参加讨论
意思是证明教授说的是对的
教授观点：铁离子的含量增加可以使得该职务生长，则找出实验失败的原因是以外即可
这实际上是让你找同意海洋学家的观点！！！！！！
D答案的意思是即便放了iron到海里面，几天后ocean currents很快会把iron从surface去掉。暗示确实缺iron，但是实验投放的iron被currents去掉了，没有发挥该发挥的作用。所以实验结果并不能说明oceanographers的假设有错。
这些人观点的推理方式是相关-因果 因为iron 数量有关系 所以推断 因果 是iron作用--数量 D是他因 解释了题目为啥iron不产生作用 实质上意思就是iron有作用
和
选项ocean currents displaced the iron-rich water from the surface
真的不矛盾吗？原文规定浓度高了，选项说漂走了，浓度还怎么高？做题的时候就郁闷了半天