GWD-28-19<---ethyl更改标题（还有GWD28-19呢？）

xinfaxian

28-19: 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?

A: Not all of the nitrogen compounds that are sometimes found in relatively high concentrations in the oceans are nutrients for plankton.

B: Certain areas of the ocean support an abundance of plankton despite having particularly low concentrations of iron.

C: The release of the iron compounds did not increase the supply of nitrogen compounds in the area.

D: A few days after the iron compounds were released, ocean currents displaced the iron-rich water from the surface.

E: The iron compounds released into the area occur naturally in areas of the ocean where plankton thrive.

chenfruit

以下是引用fengxiany在2005-10-11 5:07:00的发言：
为什么不选B?哪位能给一个不选B的理由?

B是support!

題目結論:只有Iron 並不能增加P, iron不是造成P上升的必要條件

B選項: 有些地方沒有iron 也有plankton !

            那就是說, iron不是造成P上升的必要條件

C選項承認只有Iron 並不能增加P, 必須 N + I --->上升!   

支持原結論! 只有Iron 並不能增加P! iron不是造成P上升的必要條件 所以C也是support!

D選項 利用另有它因造成Iron濃度不高...原結論不成立

[此贴子已经被作者于2005-10-23 7:44:46编辑过]

howardwang

理应是D

xinfaxian

呵呵，又一样，偶也选D.

岁寒三宝

哪位好心人给讲讲为啥选D？D的内容看不懂

vacationer

不明白呀

howardwang

本题其实就是要支持oceanographers hypothesize that this shortage of iron prevents plankton from thriving. （双重否定后）

所以，你就要解释为什么an experimental release of iron compounds into one such area failed to produce a thriving plankton population, even though local iron concentrations increased immediately.

而D说A few days after the iron compounds were released, ocean currents displaced the iron-rich water from the surface.

且Plankton generally thrive in areas of the ocean with sufficient concentrations of certain nitrogen compounds near the surface where plankton live.

所以是D

mojomojo

我也选C

fengxiany

为什么不选B?哪位能给一个不选B的理由?

Jackie2005

我选C