大家再看看gwd28-28

zhanghaolin

Which of the following most logically completes the argument?

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants.
Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert.
Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

A       histidine is found in all parts of the plant—roots, stem, leaves, and flowers

B      the herb’s high level of histidine production is found to be associated with an unusually low level of production of other amino acids

C     others of the closely related group of plants are also found to produce histidine in large quantities

D     cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic

E     the concentration of histidine in the growing herb declines as the plant approaches maturity

这道题争议很大,选A,C,D,E的都有,但支持A的人最少,不过我看到一个支持A的MM强调了一些信息,让我觉得A或者确实是正确答案,请大家再来讨论讨论.
结论是最关键的:the herb’s high histidine production is what allows it to grow in metal-rich soils
我们不能忽略这个单词high,我觉得high histidine和histidine是有区别的,如果读出结论真正强调的东西是这种草的high histidine production是它存活的关键,那么答案就是A.
open to discuss

saffsa761

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants.
Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert.
Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.
The answer should be C. ignore the yellow part and pay attention to the green marked one. the clause modifying the "plants" in green is the key for comprehending the question. the real clue of the question is that this herb which has been put under test in lab is a typical example of a group of plants that have the same living conditions which differentiated them from other plants. Therefore, the hypothesis based on the unusual discovery made on the herb will be strengthened if the discovery is a shared character of this special group of plants.   
frankly speaking, we can ignore the word "high", since whether other groups of plants contain H is an information not touched by the statement of the question. therefore, the role of the level of H can't be taken as your reasons. Moreover, in A: "in all parts" doesn't necessarily mean the herb has a high content of H.

zhanghaolin

A: "in all parts" doesn't necessarily mean the herb has a high content of H.

这句话说服了我排除A

确定选C了

xuyuanwai

这题明显选E么，大家看

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants.
Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert.
Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

原文的结论是therefore 是因为herb的高Histidine使得它在metal rich soils 中生长。

A 说H这个东西在herb的很多地方能够发觉。（这和能让他生长之间要加进去很多很多的假设。）

B说这种herb的H的含量高伴随这其他氨基酸含量的低。（这比Ａ差得更远了）

Ｃ说和herb相近的那些植物都分泌大量的H。（这个要成立要加上 其他和他相近的植物都可以在那种土壤里生存。）

D说种过herb的土壤当把他拿掉以后就可以种其他的植物了！（这个也要加上 正是因为herb分泌了高的Histidine所以使得土壤怎么样了）

E说随着H的生长，H减少了，直到herb成熟。（这不是不用加东西么herb生长他分泌H，herb不生长他不分泌H.不是什么东西都不用加么最直接）

以上想法均来自GWD，不知道有没有表达清楚。希望对大家有帮助

ItalyPirlo

我仔细想了一想，应该是E 吧。  因为 文中说了  the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert.  这种东西可以产生H，使得M的毒素减少。 那么在生长的过程中，H的减少说明了上诉的原因是对了。而其他的选项并没有直接的关系。

HenriWilligS

The problem with E is the following:
Based on the fact stated in the stimulus, histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert. The conclusion of the argument is: the herb’s high histidine production is what allows it to grow in metal-rich soils.

If E is right, then when the herb matures, it will not produce large enough amount of histidine to protect the herb from the metals in the environment. If that is true and the herb lives in a metal-rich places, it casts doubts on the hypothesis that the production of histidine is necessary for the herb to survive.

So E is out.

C is the right answer.

mslancaster

the herb’s high histidine production is what allows it to grow in metal-rich soils
结论不就是针对the herb么？！
A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants.这句话主要也就是说the herb能在含有毒金属的土壤中thrive,怎么就能把注意力转移到others of the closely related group of plants上呢？它们产生histidine，the herb也能产生 histidine，它们都有 histidine，都能在有毒金属土壤中thrive，就能证明是 histidine造成的了？~~~不太懂还是。。。还是说C想证明the herb in test-tube solutions产生的histidine在自然环境中也能产生？~~那么D似乎更直接一些啊，直接针对the herb...

fantasy1989

选D 因为文中有一个关键点说 “an amino acid that, in test-tube solutions, renders these metals chemically inert” ：氨基酸在试管的溶液中使金属的化学属性惰化。这个东西证明不是植物让自己没有毒性，它让周围的环境发生变化。所以理解了这点，就很容易想到其他植物如果种在相同的重金属环境下没有问题，就证明它的确改变了环境。

mslancaster

Guys, this is a sufficient assumption question. All you need to do is to plug in each answer choice and see if you can complete the conclusion in the stimulus.

Try it.