职称英语考试

试题来源：职称英语模拟题-理工类-阅读理解

Plant Gas

Scientists have been studyingnatural sources of methane for decades but hadn't regarded plants as aproducer'notes Frank Keppler'a geochemist at the Max Planck Institute forNuclear Physics in Heldelberg'Germany.Now Keppler and his colleagues find thatplants'from grasses to trees'may also be sources of the greenhouse gas.This isreally surprising'because most scientists assumed that methane productionrequires an oxygen-free environment.

Previously'researchers hadthought that it was impossible for plants to make significant amounts of thegas.They had assumed that microbes2 need to be in environments without oxygento produce methane.Methane is a greenhouse gas'like carbon dioxide.Gases suchas methane and carbon dioxide trap heat in Earth's atmosphere and contribute toglobal warming.

In its experiments'Keppler'steam used sealed chambers that contained the same concentration of oxygen thatEarth's atmosphere has.They measured the amounts of methane that were releasedby both living plants and dried plant material'such as fallen leaves.

With the dried plants'theresearchers took measurement at temperatures ranging from 30 degrees Celsius to70 degrees C.At 30 degrees C'they found'a gram of dried plant material releasedup to 3 nanograms of methane per hour.（One nanogram is a billionth of a gram.） With every 10-degree rise in temperature'the amount of methanereleased each hour roughly doubled.

Living plants growing at theirnormal temperatures released as much as 370 nanograms of methane per gram ofplant tissue per hour.Methane emissions tripled when living and dead plant wasexposed to sunlight.

Because there was plenty ofoxygen available'it's unlikely that the types of bacteria that normally makemethane were involved.Experiments on plants that were grown in water rather thansoil also resulted in methane emissions.That's another strong sign that the gascame from the plants and not soil microbes.

The new finding is an"interesting observation," says Jennifer Y.King'a biogeochemist atthe University of Minnesota in St.Paul3.Because some types of soil microbesconsume methane'they may prevent plant-produced methane from reaching theatmosphere.Field tests will be needed to assess the plant's influence'shenotes.（367words）

1.that was scientists'understanding of methane?

A）It was produced from plants.

B）It was not a greenhouse gas.

C）It was produced in oxygen-freeenvironments.

D）It traps more heat than any othergreenhouse gas.

2.To test whether plants are asource of methane'the scientists created

A）a oxygen-free environment.

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

C）a carbon dioxide-free environment.

D）an environment filled with the greenhousegas

3.hich statement is true of themethane emissions of plants in the experiment?

A）The lower the temperature'the higher theamount of methane emissions.

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

C）When exposed to sunlight'plants stopreleasing methane.

D）The higher the temperature'the greaterthe amount of methane emissions.

4.What of the following aboutmethane 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 pointof 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……

试题出处：http://www.examtiku.com/shiti/167945919.html
网考网参考答案：C、B、D、D、C
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大数据分析：根据网考网与考试题库的统计，该试题：
47%的考友选择了A选项
28%的考友选择了B选项
7%的考友选择了C选项
18%的考友选择了D选项
考友解析与评论：
 · 我也是C、B、D、D、C，是不是标准答案，晕
 · 我也选错了，不过这个题书上有原话
 · 我也是这么错的