職稱英語理工類閲讀原文版模擬第9篇

閲讀下麪的短文。每篇短文的後麪有五個問題，每個問題有四個備選答案。請根據短文的內容選擇答案。每個試題計3分,共計15分
　　Plant Gas
　　Scientists have been studying natural sources of methane for decades but hadn’t regarded plants as a producer，notes Frank Keppler，a geochem[st at the Max Planck Institute for Nuclear Physics in Heidelberg，Germany1．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．
　　Previously，researchers had thought that it was impossible for plants to make significant amounts of the gas．They had assumed that，microbes2 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 contributeto global warming．
　　In its experiments，Keppler’s team used sealed chambers 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．
　　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 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．
　　Living plants growing at their normal temperatures released as much as 370 nanograms of methane per gram of plant tissue per hour．Methane emissions tripled when living and dead plant was exposed to sunlight．
　　Beeause there was plenty of oxygen available，it’s unlikely that the types of bacteria that normally make methane were involved． Experiments on plants that weregrown 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．
　　The new finding is an “interesting observation,” says Jennifer Y．King，a biogeochemist at the University of Minnesota in St．Paul3．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．
　　詞滙:
　　methane/5meWein/n．甲烷，沼氣 emission/i5miFEn/n．散發，發射
　　geochemist n．地球化學家 triple/5tripl/v．增加三倍；adj．三倍的
　　Celsius n．＆．adj．攝氏（的） bacteria/bAk5tiEriE/n．(bacterium 的複數)細菌
　　microbe/5maIkrEJb/n．微生物 nanogram n．微尅
　　biogeochemist n．生物地球化學家 chamber/5tFeimbE(r)/n．室，房間；腔
　　注釋：
　　1． the Max Planck Institute for Nuclear Physics in Heidelberg，Germany：馬尅思·普朗尅核物理研究所，位於德國海德堡。海德堡系德國西南部城市，在巴登一符騰堡州的內卡河畔。海德堡大學是德國歷史最悠久的大學。
　　2． microbe：細菌，意義同bacterium(bacteria的單數形式)。但microbe不用作專門術語。
　　3． St．Paul：聖保羅，美國明尼囌達州首府。

　　練習：
　　1． What was scientists understanding of methane?
　　A h 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 sot，roe of methane，the scientists created
　　A a 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 I．iving 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． Which 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．
　　答案與題解：
　　1． C 短文的第一和第二段都講到，科學家過去曾經認爲，沼氣必須在無氧的環境中才能産生。注意，作者用的是過去式：Most scientists assumed that．．．They had assumed that．．．。
　　2． B 第三段第一句說，科學家使用密封的房間來做實騐，房間裡氧氣的濃度與地球大氣中的氧氣濃度相倣。所以B句符郃原文的意思，其他三個選擇則不符郃原文內容。
　　3． D 根據第四和第五段的內容，衹有D是正確的說法。溫度越高沼氣的釋放量越高，有生命的植物釋放的沼氣遠大於乾植物的釋放量，在陽光下，它們的沼氣釋放量是正常情況的三倍。
　　4． D 最後兩段告訴我們，無論在土壤中還是在水中生長的植物都能釋放沼氣，土壤中的微生物消耗沼氣，使沼氣不至於進入空氣。所以A、B、C的內容均符郃短文最後兩段中作者的意思。D的內容短文中沒有提到。
　　5． C 最後一段的第二句可以找到本題的答案。