C) others of the closely related group of plants are also found to produce histidine in large quantities Other plants能够创造histidine,不能表达hisidine跟生长有关
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 histidine随着植物生长到成熟,浓度开始下降。说明植物生长过程中histidine开始减少,减少部分去跟土壤中的金属进行化学反应(an amino acid that, in test-tube solutions, renders these metals chemically inert)。而生长跟土壤有关,histidine跟植物本身有关,两者关联起来,support了结论
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.
看这句就知道了,that从句的主语是plants而不是one,因为谓语是复数
所以说a group of closely related plants 都是能在metal中生存的。
我的一票投给D. 理由: 选项必须支持2个东西(Histidine以及metal)的暧昧关系, 要不这对狗男女的关系都需要主观推断, 没有捉奸在床的来的可靠. A. plant的各部位含量, 未提及Histidine B. other animo acid,关Histidine鸟事 C. other plant,关本plant鸟事 E. 没提METAL,怎知道Histidine以及metal是狗男女有猫腻? D. Histidine以及metal的关系确凿,已经造成了影响——别的植物也能在这里长了。Histidine以及metal确有关系无疑——支持!
C有个问题,有可能其他每种植物都有自己的看家本领对抗metals ,而不是因为他们有histidine。只是因为他们同属于one of a group of closely related plants,所以才都 produces large amounts of histidine。不能证明herb的histidine是他对抗metals 的原因,因为herb也可能有除histidine之外的独门绝技对抗metals。
本题提干里说histidine在实验室里(test-tube solutions)能钝化metals,但这句话不能证明在histidine实际生长土壤中(metal-rich soils)也能钝化metals。而hypothesis正是histidine production is what allows it(herb) to grow in metal-rich soils
而D说histidine不但在实验室里能钝化metals,在实际生长土壤中也能完成这一动作,因为其他不能钝化metals的植物能在“曾被herb的histidine钝化过的土壤中”生长。这正好support hypothesis:herb’ s high histidine production is what allows it to grow in metal-rich soils
其他选项错误原因: A 根茎叶花都含有histidine无法证明histidine能怎样,根茎叶花含还都含有水分呢,不能因此证明水能怎样。 B low level of production of other amino acids是无关内容 C 上面说过了 D 正确 E histidine随着生长减少也无法证明histidine能怎样,水分随着生长也会减少,不能因此证明水能怎样。