28. GWD28-Q28,一道纠结的CR，值得讨论下

Cherliuiking

28. GWD28-Q28:
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.（惰性）  ossibly, 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
我选D，有人说选E，到底选哪个呢？大家讨论呀

prayer

我在C和E里分不清，D我认为不对，是因为

therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

假设一定要架桥，histidine与grow之间的关系。D说种过这个草的土可以适合别的草长，跟histidine有什么关系，不应该作为假设存在，如果是support，那么D就对。

最后，我又看了看别的讨论帖子，什么答案的都有，不过有个选E的解释很好。

The key is in the question itself..

"the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if"


The hypothesis is in bold-faced text above... if it allows it to grow, then it is also the reason for its saturation (maturity, death if i should say), in growth.. E states that precisely!

mature² v

[I]
to become fully grown or developed

Cherliuiking

histidine的作用在于 renders these metals chemically inert，减少金属的化学活性，所以这种植物所在的土地的金属的化学毒性减小了，甚至，那些怕化学毒性的植物都能生长了，我本来是这样想的，LS的nn觉得为啥不对呢？

Cherliuiking

或者
therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.
E可否这样理解，上面的|grow是的是在成熟前的那部分，成熟了也许就以为这停止生长了，所以长的时候有，不长了就没有了

pammy0926

it produces large amounts of histidine, an amino acid that....renders these metals chemically inert.
我的理解是：这个植物用自己分泌的histidine来换取了金属物毒性的减少。同时，土壤里的金属物质没有一直增加（文中没有提及这个因素），那就意味着，随着植物的成长，分泌的histidine是在减少的，减少的东西都是用来化解金属了。慢慢的，金属毒性没有了，那也没必要继续分泌histidine了。
我感觉E正确噢。

prayer

或者
therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.
E可否这样理解，上面的|grow是的是在成熟前的那部分，成熟了也许就以为这停止生长了，所以长的时候有，不长了就没有了

-- by 会员 Cherliuiking (2010/2/1 14:32:39)

是的，这道题就是这个意思。grow停止了，就只剩下being alive

Cherliuiking

呵呵，我明白了，谢谢NN们，明天就考，希望能给大家带回来狗狗

shadow影

IMO E

focus on the conclusion: just about H and GROW!

C.Incorrect : OTHERS IN THE GROUP produce H, but what about H -> GROW?

E.Correct : It is stated in the hypotheses above that histidine allows the herb to GROW. It means that as long as the herb is growing, histidine is high and as the herb approaches MATURITY the concentration of histidine declines.

akiluk

大家认真看一下题~
A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals.
后面的thrive in soil with high concentrations 修饰的是 a group of closely related plant
文章说 a group 里的一种 herb 因为 histidine可以生长 ，得出（group 中的其他植物也是）因为H这种物质而得以生长，有gap!!
所以选C   group 中的其他植物都有H这种物质  这样就可以推出是因为H物质。

hjxsparrow

正解必须是D

首先题目要我们加强的是一个hypothesis
这个hypothesis题中给的是the herb’s high histidine production is what allows it to grow in metal-rich soils.（h是该植物成活的原因）

题干中关于h的作用的描述只有an amino acid that, in test-tube solutions, renders these metals chemically inert. 就是说h可以使得这些metal 化学活性变惰

那么现在要加强这个假说只需要加强 是因为h的这种特殊作用导致该植物可以生存，那么其他植物也可以在这种土壤里生存，也就说明了土壤里的metal chemically inert，证明是h使得该植物适宜在此土壤中生存

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至于C。这类植物还都长叶子呢，难道就可以说它们是因为都长叶子所以就可以在这种土壤里生存么