Day 6

实战演练

When marine organisms called phytoplankton photosynthesize, they absorb carbon dioxide dissolved in seawater, potentially causingAreduction in the concentration of atmospheric carbon dioxide,Agas that contributes to global warming.However, phytoplankton flourish only in surface waters where iron levels are sufficiently high.Martin therefore hypothesized that adding iron to iron-poor regions of the ocean could help alleviate global warming.While experiments subsequently confirmed that suchAprocedure increases phytoplankton growth, field tests have shown that such growth does not significantly lower atmospheric carbon dioxide.When phytoplankton utilize carbon dioxide for photosynthesis, the carbon becomesAbuilding block for organic matter, but the carbon leaks back into the atmosphere when predators consume the phytoplankton and respire carbon dioxide.

——GRE OG 2nd Edition, Practice Test 1, Section 4, Verbal Reasoning

It can be inferred that the author of the passage mentions predators primarily in order to

A.help explain why Martin's hypothesis is incorrect.

B.identify one effect of adding iron to iron-poor waters.

C.indicate how some carbon dioxide is converted to solid organic matter.

D.help account for differences in the density of phytoplankton between different regions of the ocean.

E.point outAfactor that was not anticipated by the scientists who conducted the field tests mentioned in the passage.

答案：A

答案解析

题目考查为什么会提到“predators”，其实也就是在问为什么会提到“predators通过呼吸将二氧化碳释放回大气中”。浅层的目的自然是进一步说明上一句提到的“浮游生物的增长没有明显降低大气中的二氧化碳”，根据这点很容易选择选项B“识别向缺铁的水里加入铁后的一种效果”或选项E“指出进行现场试验的科学家没有预料到的一个因素”。但这并不是最终的目的，仔细读文章可以知道，证明“浮游生物的增长没有明显降低大气中的二氧化碳”的目的其实是反驳Martin的假设，因为出现的这种结果是和前面Martin假设的向缺铁的水里加入铁有助于缓解全球变暖的预期不一样的，所以最终证明了Martin的假设是不对的，因此选项A“帮助解释为什么Martin的假设是错的”是正确答案。选项C“说明一些二氧化碳如何被转化成固体有机物”及选项D“说明海洋不同区域浮游生物密度的差别”在文中并未涉及。

英文重现

While experiments subsequently confirmed that suchAprocedure increases phytoplankton growth, field tests have shown that such growth does not significantly lower atmospheric carbon dioxide.When phytoplankton utilize carbon dioxide for photosynthesis, the carbon becomesAbuilding block for organic matter, but the carbon leaks back into the atmosphere when predators consume the phytoplankton and respire carbon dioxide.

解析

1.本句中的“experiment”和“field test”意思都是试验，但是前者主要指在实验室中做的试验，后者指在现场做的试验。

2.前面我们讲过“while”作并列连词表示转折，前后内容形成对比的用法，但在这里，“While experiment…phytoplankton growth”中的“while”的却是另一个用法，即引导让步状语从句，意思为“虽然……，但是……”，多用于句首。

3.第二个句子的两个“when”都是用来引导时间状语从句，表示“当……时”，另外“when”也可以引导定语从句，其先行词一般是一些表示时间的词，在从句中充当时间状语，如：“I still remember the day when I first met you.”（我仍然记得初次与你见面的那天）。

4.“leak into”意思为“泄露、渗入”。例如：

Water had started to leak into the basement.

水已经开始渗入地下室了。

词义辨析

参考翻译

虽然试验随后证实了这一做法加速了浮游生物的生长，但是现场试验却显示这种生长并没有明显降低大气中的二氧化碳。当浮游生物利用二氧化碳进行光合作用时，碳会变成有机物的基本组成部分，但是当掠食者食用浮游生物并呼吸出二氧化碳时，碳会再次泄露回大气中去。