学位英语

Plant Gas

1. Scientists have been studying natural sources of methane(甲烷，沼气) for decades but hadn’t regarded plants as a producer, notes Frank Keppler, a geochemist(地球化学家) at the Max Planck Institute for Nuclear Physics in Heldelberg, Germany. Now Keppler and his colleagues find that plants, from grasses to trees, may also be sources of the greenhouse gas. This is really surprising, because most scientists assumed that methane production requires an oxygen-free environment.

2. Previously, researchers had thought that it was impossible for plants to make significant amounts of the gas. They had assumed that microbes(微生物) need to be in environments without oxygen to produce methane. Methane is a greenhouse gas, like carbon dioxide. Gases such as methane and carbon dioxide trap heat in Earth’s atmosphere and contribute to global warming.

3. In its experiments, Keppler’s team used sealed chambers (室，房间;腔) that contained the same concentration of oxygen that Earth’s atmosphere has. They measured the amounts of methane that were released by both living plants and dried plant material, such as fallen leaves.

4. With the dried plants, the researchers took measurement at temperatures ranging from 30 degrees Celsius to 70 degrees C. At 30 degrees C, they found, a gram of dried plant material released up to 3 nanograms(微克) of methane per hour. (One nanogram is a billionth of a gram.) With every 10-degree rise in temperature, the amount of methane released each hour roughly doubled.

5. Living plants growing at their normal temperatures released as much as 370 nanograms of methane per gram of plant tissue per hour. Methane emissions(散发，发射)tripled(增加三倍;) when living and dead plant was exposed to sunlight.

6. Because there was plenty of oxygen available, it’s unlikely that the types of bacteria(bacterium的复数，细菌) that normally make methane were involved. Experiments on plants that were grown in water rather than soil also resulted in methane emissions. That’s another strong sign that the gas came from the plants and not soil microbes.

7. The new finding is an “interesting observation,” says Jennifer Y. King, a biogeochemist(生物地球化学家) at the University of Minnesota in St. Paul. Because some types of soil microbes consume methane, they may prevent plant-produced methane from reaching the atmosphere. Field tests will be needed to assess the plant’s influence, she notes.

注释：

1. the Max Planck Institute for Nuclear Physics in Heldelberg, Germany：马克思·普朗克核物理研究所，位于德国海德堡。海德堡系德国西南部城市，在巴登-符腾堡州的内卡河畔。海德堡大学是德国历史最悠久的大学。

2. microbe：细菌，意义同 bacterium(bacteria的单数形式)，但 microbe 不用作专门术语。

3. St. Paul：圣保罗，美国明尼苏达州首府。

练习：

1. What was scientists’ understanding of methane?

A) It was produced from plants.

B) It was not a greenhouse gas.

C) It was produced in oxygen-free environments.

D) It traps more heat than any other greenhouse gas.

2. To test whether plants are a source of methane, the scientists created ______.

A) an oxygen-free environment.

B) an environment with the same concentration of oxygen as the Earth has.

C) a carbon dioxide-free environment.

D) an environment filled with the greenhouse gas

3. Which statement is true of the methane emissions of plants in the experiment?

A) The lower the temperature, the higher the amount of methane emissions.

B) Living plants release less methane than dried plants at the same temperature.

C) When exposed to sunlight, plants stop releasing methane.

D) The higher the temperature, the greater the amount of methane emissions.

4. What of the following about methane is Not mentioned in the passage?

A) Plants growing in soil release methane.

B) Plants growing in water release methane.

C) Soil microbes consume methane.

D) Microbes in plants produce methane.

5. What is the beneficial point of some microbes consuming plant-produced methane?

A) Methane becomes less poisonous.

B) Methane is turned into a fertilizer.

C) Less methane reaches the atmosphere.

D) Air becomes cleaner.

题目详解：

1.先看标题，推测文章主题：Plant(植物) Gas(气体)，即植物能产生某种气体。什么气体?我们很快扫视文章发现文中有一个词共出现了14次，它就是Methane(沼气，学名甲烷)，因此标题中的gas就是指Methane。我们知道城市垃圾、煤矿、碳泥沼等会产生甲烷，从未听说植物有这种可能性。所以可以说这是人类的又一次新的发现，它有助于我们重新认识全球变暖与温室气体之间的关系。

2.接下来看问题，了解它们的类型，要针对问题的提法对症下药。通读后我们发现，五个问题仍是细节题为主，这样我们就可以一边按文章的写作顺序精读，一边准确回答问题。而且，我相信大家还会学到不少新的词汇和知识!

3.看第1题：

What was scientists’ understanding of methane?科学家们对于沼气过去有什么样的理解?(注意谓语动词时态!)

A) It was produced from plants.它是由植物产生的。

B) It was not a greenhouse gas.它不是温室气体。

C) It was produced in oxygen-free environments. 它是在缺氧环境中产生的。

D) It traps more heat than any other greenhouse gas.它比其它任何一种温室气体吸热都多。

阅读第一段：

Scientists have been studying(完成进行时，一直研究。。。) natural sources(来源，注意和resource资源对比，) of methane(甲烷，沼气) for decades(是decade的复数形式，几十年) but hadn’t regarded (过去完成时，强调过去的过去，即曾经不认为。。。)plants as (作为)a producer(制造者、产生者), notes(指明、表明) Frank Keppler, a geochemist(地球化学家) at the Max Planck Institute for Nuclear Physics in Heldelberg(海德堡), Germany(德国).(中心句) Now (现在，和前面内容从时间上形成对比。)Keppler and his colleagues find that plants, from grasses to trees, may also be sources of the greenhouse gas. This is really surprising(令人吃惊的), because(解释原因)1>. most scientists assumed(注意时态，表示过去认为, assume = think) that methane production(产生) requires(动词，和need同义) an oxygen-free(缺氧的) environment(环境).

结论：我们初步可以断定答案是C。而通过做这一题，我们真正地可以认识到基本英语语法的重要性了。当一句话中的动词使用不同时态时，就是在表达不同时间段发生的动作，即使句中没有时间状语。因此，我仍然希望大家要有坚实的基本功。

4.看第2题：

To test whether plants are a source of methane, the scientists created ______.

为了去检测是否植物是沼气的来源，科学家们创造了______.

A) an oxygen-free environment.缺氧的环境

B) an environment with the same concentration of oxygen as the Earth has.

一种氧气的浓度与地球大气中的氧气浓度一样的环境

C) a carbon dioxide-free environment. 缺二氧化碳的环境

D) an environment filled with the greenhouse gas

充满了温室气体的环境

分析：标准的细节题，要想得到答案只有继续阅读文章。

第2段：

Previously(以前), researchers had thought (曾经认为)that it was impossible(不可能的) for plants to make significant(有意义的、重要的) amounts(数量) of the gas. They had assumed that microbes(微生物) need to be in(在。。。之中) environments without (没有)oxygen(氧气) to produce methane. Methane is a greenhouse gas, like carbon dioxide(二氧化碳). Gases such as(例如) methane and carbon dioxide trap heat(吸收热量) in Earth’s atmosphere(大气层)and contribute to(导致、引起)global warming(全球变暖).

结论：事实上，这一段仍然在回答第一题。从侧面我们也可以更加确定刚才的答案是正确的。还是要注意所有动词的时态!我们并未找到第二题答案，因此继续!

第三段：

2>. In its experiments(实验), Keppler’s team used(使用) sealed(原形seal，密封) chambers (室，房间) that(引导定语从句) contained(包含、包括) the same concentration(密度) of oxygen that(引导定语从句， 修饰concentration) Earth’s atmosphere(大气、大气层) has. They measured (测量、衡量)the amounts(数量) of methane that(引导定语从句， 修饰the amounts) were released(释放) by both living plants(活着的植物) and dried(干的) plant material(材料), such as fallen leaves(落叶).

结论：开头的第一句就揭示了答案应该是B。

5.看第3题：

3. Which statement is true of the methane emissions of plants in the experiment?

在实验中，有关植物释放沼气的陈述，哪一个是正确的?

A) The lower the temperature, the higher the amount of methane emissions.

温度越低，沼气的释放量越高。

B) Living plants release less methane than dried plants at the same temperature.

在相同的温度下，活着的植物要比干植物释放的沼气少。

C) When exposed to sunlight, plants stop releasing methane.

当植物暴露于阳光之下时，就停止释放沼气。

D) The higher the temperature, the greater the amount of methane emissions.

温度越高，沼气的释放量越高。

分析：这道题中有三个关键词：methane emissions，Living plants，dried plants。因此要得出答案，必须读4，5两段。

读第四段：

With(至于) the dried plants, the researchers took measurement(进行测量) at temperatures(温度) ranging from (从。。。范围到。。。范围)30 degrees Celsius(30℃) to 70 degrees C(70℃). At 30 degrees C, they found, a gram(克) of dried plant material released up to(多达)3 nanograms(微克) of methane per hour(每小时). (One nanogram is a billionth(十亿分之一) of a gram.) With every 10-degree(度) rise(上升) in temperature, the amount of methane released each hour roughly(大约)doubled(两倍).

第五段：

Living plants growing at their normal(正常的) temperatures released as much as(像。。。一样多) 370 nanograms of methane per gram of plant tissue(每一克的植物组织) per hour. Methane emissions(散发，发射)tripled(增加三倍;) when living and dead plant was exposed to(暴露于。。。之下) sunlight.

结论：这道题要答对，这两段一定要全部看懂。我们可以得出结论温度越高沼气的释放量越高，有生命的植物释放的沼气远大于干植物的释放量，在阳光下，它们的沼气释放量是正常情况的三倍。因此D是正确答案。

6.看第四题：

What of the following about methane is Not mentioned in the passage?

下列关于沼气的内容哪一个没有在文章中被提到?

A) Plants growing in soil release methane.在土壤中生长的植物释放沼气。

B) Plants growing in water release methane. 在水中生长的植物释放沼气。

C) Soil microbes consume methane.土壤微生物消耗沼气。

D) Microbes in plants produce methane.植物中的微生物产生沼气。

读第6段：

Because there was plenty of (足够的、充足的)oxygen available(可以得到的), it’s unlikely(不可能的) that the types(种类) of bacteria(bacterium的复数，细菌) that(引导定语从句) normally(正常地) make methane were involved(被涉及，包含). Experiments on plants that(引导定语从句， 修饰plants) were grown in water rather than(而不是) soil also resulted in (引起、导致，同义词cause, contribute to)methane emissions. That’s another strong sign(迹象) that(引导的是同位语从句，对sign进行具体的解释，说明)4>. the gas came from the plants and not soil microbes(气体产生于植物并不是土壤微生物。).

结论：通过阅读这一段，分析得出答案D的表述与原文是不吻合的，因此选择D。

7.看第五题：

What is the beneficial point of some microbes consuming plant-produced methane?

一些微生物在消耗由植物产生的沼气时有什么好处?

A) Methane becomes less poisonous.沼气的毒性减少。

B) Methane is turned into a fertilizer. 沼气被转化成肥料。

C) Less methane reaches the atmosphere.到达大气中的沼气会减少。

D) Air becomes cleaner.空气变得更干净了。

最后一段：

The new finding(发现) is an “interesting observation(观察),” says Jennifer Y. King, a biogeochemist(生物地球化学家) at the University of Minnesota in St. Paul.

5>. Because some types(种类) of soil microbes consume(消耗) methane, they may prevent(阻止某事的发生) plant-produced methane from reaching(到达) the atmosphere. Field (土地)tests will be needed to assess(确定、估计) the plant’s influence(影响), she notes.

结论：很容易得到答案是C。

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