GWD2-19 很少有人问过，不过我很迷惑阿，请教！

cherrychengyue

Q19:

Sunflowers growing in pots were placed, with their roots submerged, in the pond contaminated with radioactive elements.  The sunflowers kept growing; in the process, they absorbed radioactive elements.  Within twelve days, 85 percent of the radioactive elements were removed from the water, which is no less than can be accomplished with the much more expensive conventional filtration techniques.  Scientists therefore propose using sunflowers for decontamination wherever there are radioactively contaminated ponds.

Which of the following, if true, points to a limitation on the applicability of the proposed method of decontamination?

1. Some plants other than sunflowers can also remove radioactive elements from water.


2. The water in many ponds contaminated with radioactive elements is so cold that it would kill sunflowers whose roots were submerged in it.


3. Sunflowers that grow with their roots submerged in water grow less well than sunflowers growing under optimal conditions on dry land.


4. Only species of sunflowers with large leaves can have their roots submerged in water and still keep growing.


5. In ponds in which the circulation of the water is artificially increased, sunflowers absorb radioactive elements far faster than they do in other ponds.

B是答案，但原文并没有说花会被冻死，是不是超出范围了啊。

E为什么不对呢，可能科学家为了实验人为加大了辐射浓度，而现实中效果不会那么快，所以实施有限制。

请指教谢谢

[此贴子已经被作者于2005-9-2 21:56:29编辑过]

nickt

B -因为在某些pond里sunflower 不能"kept growing",所以不能起作用.

cherrychengyue

E为什么不对呢

寂寞的声音

题干中并没有说water和absorb的关系， 我理解这2个咚咚是无关的， 自然无法说明是一个limitaion， 相反， B中说把花给kill掉了，由题干说，花是吸收radioactive的， 那么花没了， 也就吸收不了radioactive了， 所以B是个limitation。

cherrychengyue

有阿 they absorbed radioactive elements.

oceanalma

E不对因为faster跟absord没有冲突，慢点也能吸收，题目中并没有说时间是影响结论的因素

billytang1980

我也觉得有问题，选了D，但是这个题目讨论的人都不见了，可怜啊！！！

十二月风暴

结论：以后可以用向日葵消除污染。

this argument focuses on the decontamination rather than the growth of sunflowers.

后者无关选项。

而B，死了=不能decontamination