Plant Gas
1. Scientists have been studying natural sources of methane(甲烷，沼氣) for decades but hadn’t regarded plants as a producer, notes Frank Keppler, a geochemist（地球化學家） 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，房間；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（散發(fā)，發(fā)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的復數(shù)，細菌） 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（生物地球化學家） 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.
注釋：
1. the Max Planck Institute for Nuclear Physics in Heldelberg, Germany：馬克思?普朗克核物理研究所，位于德國海德堡。海德堡系德國西南部城市，在巴登－符騰堡州的內(nèi)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(shù)形式），但 microbe 不用作專門術(shù)語。
3. St. Paul：圣保羅，美國明尼蘇達州首府。
練習：
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.
題目詳解：
1．先看標題，推測文章主題：Plant(植物) Gas（氣體），即植物能產(chǎn)生某種氣體。什么氣體？我們很快掃視文章發(fā)現(xiàn)文中有一個詞共出現(xiàn)了14次，它就是Methane（沼氣，學名甲烷），因此標題中的gas就是指Methane。我們知道城市垃圾、煤礦、碳泥沼等會產(chǎn)生甲烷，從未聽說植物有這種可能性。所以可以說這是人類的又一次新的發(fā)現(xiàn)，它有助于我們重新認識全球變暖與溫室氣體之間的關(guān)系。
2．接下來看問題，了解它們的類型，要針對問題的提法對癥下藥。通讀后我們發(fā)現(xiàn)，五個問題仍是細節(jié)題為主，這樣我們就可以一邊按文章的寫作順序精讀，一邊準確回答問題。而且，我相信大家還會學到不少新的詞匯和知識！
3．看第1題：
What was scientists’ understanding of methane?科學家們對于沼氣過去有什么樣的理解？（注意謂語動詞時態(tài)?。?BR> A) It was produced from plants.它是由植物產(chǎn)生的。
B) It was not a greenhouse gas.它不是溫室氣體。
C) It was produced in oxygen-free environments. 它是在缺氧環(huán)境中產(chǎn)生的。
D) It traps more heat than any other greenhouse gas.它比其它任何一種溫室氣體吸熱都多。
閱讀第一段：
Scientists have been studying（完成進行時，一直研究。。。） natural sources（來源，注意和resource資源對比，） of methane(甲烷，沼氣) for decades（是decade的復數(shù)形式，幾十年） but hadn’t regarded （過去完成時，強調(diào)過去的過去，即曾經(jīng)不認為。。。）plants as （作為）a producer（制造者、產(chǎn)生者）, notes（指明、表明） Frank Keppler, a geochemist（地球化學家） at the Max Planck Institute for Nuclear Physics in Heldelberg（海德堡）, Germany（德國）.（中心句） Now （現(xiàn)在，和前面內(nèi)容從時間上形成對比。）Keppler and his colleagues find that plants, from grasses to trees, may also be sources of the greenhouse gas. This is really surprising（令人吃驚的）, because（解釋原因）1>. most scientists assumed（注意時態(tài)，表示過去認為, assume = think） that methane production（產(chǎn)生） requires（動詞，和need同義） an oxygen-free（缺氧的） environment（環(huán)境）.
結(jié)論：我們初步可以斷定答案是C。而通過做這一題，我們真正地可以認識到基本英語語法的重要性了。當一句話中的動詞使用不同時態(tài)時，就是在表達不同時間段發(fā)生的動作，即使句中沒有時間狀語。因此，我仍然希望大家要有堅實的基本功。
4．看第2題：
To test whether plants are a source of methane, the scientists created ______.
為了去檢測是否植物是沼氣的來源，科學家們創(chuàng)造了______.
A) an oxygen-free environment.缺氧的環(huán)境
B) an environment with the same concentration of oxygen as the Earth has.
一種氧氣的濃度與地球大氣中的氧氣濃度一樣的環(huán)境
C) a carbon dioxide-free environment. 缺二氧化碳的環(huán)境
D) an environment filled with the greenhouse gas
充滿了溫室氣體的環(huán)境
分析：標準的細節(jié)題，要想得到答案只有繼續(xù)閱讀文章。
第2段：
Previously（以前）, researchers had thought （曾經(jīng)認為）that it was impossible（不可能的） for plants to make significant（有意義的、重要的） amounts（數(shù)量） of the gas. They had assumed that microbes（微生物） need to be in（在。。。之中） environments without （沒有）oxygen（氧氣） 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（吸收熱量） in Earth’s atmosphere（大氣層）and contribute to（導致、引起）global warming（全球變暖）.
結(jié)論：事實上，這一段仍然在回答第一題。從側(cè)面我們也可以更加確定剛才的答案是正確的。還是要注意所有動詞的時態(tài)！我們并未找到第二題答案，因此繼續(xù)！
第三段：
2>. In its experiments（實驗）, Keppler’s team used（使用） sealed（原形seal，密封） chambers (室，房間) that（引導定語從句） contained（包含、包括） the same concentration（密度） of oxygen that（引導定語從句， 修飾concentration） Earth’s atmosphere（大氣、大氣層） has. They measured （測量、衡量）the amounts（數(shù)量） of methane that（引導定語從句， 修飾the amounts） were released（釋放） by both living plants（活著的植物） and dried（干的） plant material（材料）, such as fallen leaves（落葉）.
結(jié)論：開頭的第一句就揭示了答案應(yīng)該是B。
5．看第3題：
3. Which statement is true of the methane emissions of plants in the experiment?
在實驗中，有關(guān)植物釋放沼氣的陳述，哪一個是正確的？
A) The lower the temperature, the higher the amount of methane emissions.
溫度越低，沼氣的釋放量越高。
B) Living plants release less methane than dried plants at the same temperature.
在相同的溫度下，活著的植物要比干植物釋放的沼氣少。
C) When exposed to sunlight, plants stop releasing methane.
當植物暴露于陽光之下時，就停止釋放沼氣。
D) The higher the temperature, the greater the amount of methane emissions.
溫度越高，沼氣的釋放量越高。
分析：這道題中有三個關(guān)鍵詞：methane emissions，Living plants，dried plants。因此要得出答案，必須讀4，5兩段。
讀第四段：
With（至于） the dried plants, the researchers took measurement（進行測量） at temperatures（溫度） ranging from （從。。。范圍到。。。范圍）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（多達）3 nanograms（微克） of methane per hour（每小時）. (One nanogram is a billionth（十億分之一） of a gram.) With every 10-degree（度） rise（上升） in temperature, the amount of methane released each hour roughly（大約）doubled（兩倍）.
第五段：
Living plants growing at their normal（正常的） temperatures released as much as（像。。。一樣多） 370 nanograms of methane per gram of plant tissue（每一克的植物組織） per hour. Methane emissions（散發(fā)，發(fā)射）tripled（增加三倍；） when living and dead plant was exposed to（暴露于。。。之下） sunlight.
結(jié)論：這道題要答對，這兩段一定要全部看懂。我們可以得出結(jié)論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于干植物的釋放量，在陽光下，它們的沼氣釋放量是正常情況的三倍。因此D是正確答案。
6．看第四題：
What of the following about methane is Not mentioned in the passage?
下列關(guān)于沼氣的內(nèi)容哪一個沒有在文章中被提到？
A) Plants growing in soil release methane.在土壤中生長的植物釋放沼氣。
B) Plants growing in water release methane. 在水中生長的植物釋放沼氣。
C) Soil microbes consume methane.土壤微生物消耗沼氣。
D) Microbes in plants produce methane.植物中的微生物產(chǎn)生沼氣。
讀第6段：
Because there was plenty of （足夠的、充足的）oxygen available（可以得到的）, it’s unlikely（不可能的） that the types（種類） of bacteria（bacterium的復數(shù)，細菌） that（引導定語從句） normally（正常地） make methane were involved（被涉及，包含）. Experiments on plants that（引導定語從句， 修飾plants） were grown in water rather than（而不是） soil also resulted in （引起、導致，同義詞cause, contribute to）methane emissions. That’s another strong sign(跡象) that（引導的是同位語從句，對sign進行具體的解釋，說明）4>. the gas came from the plants and not soil microbes（氣體產(chǎn)生于植物并不是土壤微生物。）.
結(jié)論：通過閱讀這一段，分析得出答案D的表述與原文是不吻合的，因此選擇D。
7．看第五題：
What is the beneficial point of some microbes consuming plant-produced methane?
一些微生物在消耗由植物產(chǎn)生的沼氣時有什么好處？
A) Methane becomes less poisonous.沼氣的毒性減少。
B) Methane is turned into a fertilizer. 沼氣被轉(zhuǎn)化成肥料。
C) Less methane reaches the atmosphere.到達大氣中的沼氣會減少。
D) Air becomes cleaner.空氣變得更干凈了。
最后一段：
The new finding（發(fā)現(xiàn)） is an “interesting observation（觀察）,” says Jennifer Y. King, a biogeochemist（生物地球化學家） at the University of Minnesota in St. Paul.
5>. Because some types（種類） of soil microbes consume（消耗） methane, they may prevent（阻止某事的發(fā)生） plant-produced methane from reaching（到達） the atmosphere. Field (土地)tests will be needed to assess（確定、估計） the plant’s influence（影響）, she notes.
結(jié)論：很容易得到答案是C。
1. Scientists have been studying natural sources of methane(甲烷，沼氣) for decades but hadn’t regarded plants as a producer, notes Frank Keppler, a geochemist（地球化學家） 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，房間；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（散發(fā)，發(fā)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的復數(shù)，細菌） 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（生物地球化學家） 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.
注釋：
1. the Max Planck Institute for Nuclear Physics in Heldelberg, Germany：馬克思?普朗克核物理研究所，位于德國海德堡。海德堡系德國西南部城市，在巴登－符騰堡州的內(nèi)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(shù)形式），但 microbe 不用作專門術(shù)語。
3. St. Paul：圣保羅，美國明尼蘇達州首府。
練習：
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.
題目詳解：
1．先看標題，推測文章主題：Plant(植物) Gas（氣體），即植物能產(chǎn)生某種氣體。什么氣體？我們很快掃視文章發(fā)現(xiàn)文中有一個詞共出現(xiàn)了14次，它就是Methane（沼氣，學名甲烷），因此標題中的gas就是指Methane。我們知道城市垃圾、煤礦、碳泥沼等會產(chǎn)生甲烷，從未聽說植物有這種可能性。所以可以說這是人類的又一次新的發(fā)現(xiàn)，它有助于我們重新認識全球變暖與溫室氣體之間的關(guān)系。
2．接下來看問題，了解它們的類型，要針對問題的提法對癥下藥。通讀后我們發(fā)現(xiàn)，五個問題仍是細節(jié)題為主，這樣我們就可以一邊按文章的寫作順序精讀，一邊準確回答問題。而且，我相信大家還會學到不少新的詞匯和知識！
3．看第1題：
What was scientists’ understanding of methane?科學家們對于沼氣過去有什么樣的理解？（注意謂語動詞時態(tài)?。?BR> A) It was produced from plants.它是由植物產(chǎn)生的。
B) It was not a greenhouse gas.它不是溫室氣體。
C) It was produced in oxygen-free environments. 它是在缺氧環(huán)境中產(chǎn)生的。
D) It traps more heat than any other greenhouse gas.它比其它任何一種溫室氣體吸熱都多。
閱讀第一段：
Scientists have been studying（完成進行時，一直研究。。。） natural sources（來源，注意和resource資源對比，） of methane(甲烷，沼氣) for decades（是decade的復數(shù)形式，幾十年） but hadn’t regarded （過去完成時，強調(diào)過去的過去，即曾經(jīng)不認為。。。）plants as （作為）a producer（制造者、產(chǎn)生者）, notes（指明、表明） Frank Keppler, a geochemist（地球化學家） at the Max Planck Institute for Nuclear Physics in Heldelberg（海德堡）, Germany（德國）.（中心句） Now （現(xiàn)在，和前面內(nèi)容從時間上形成對比。）Keppler and his colleagues find that plants, from grasses to trees, may also be sources of the greenhouse gas. This is really surprising（令人吃驚的）, because（解釋原因）1>. most scientists assumed（注意時態(tài)，表示過去認為, assume = think） that methane production（產(chǎn)生） requires（動詞，和need同義） an oxygen-free（缺氧的） environment（環(huán)境）.
結(jié)論：我們初步可以斷定答案是C。而通過做這一題，我們真正地可以認識到基本英語語法的重要性了。當一句話中的動詞使用不同時態(tài)時，就是在表達不同時間段發(fā)生的動作，即使句中沒有時間狀語。因此，我仍然希望大家要有堅實的基本功。
4．看第2題：
To test whether plants are a source of methane, the scientists created ______.
為了去檢測是否植物是沼氣的來源，科學家們創(chuàng)造了______.
A) an oxygen-free environment.缺氧的環(huán)境
B) an environment with the same concentration of oxygen as the Earth has.
一種氧氣的濃度與地球大氣中的氧氣濃度一樣的環(huán)境
C) a carbon dioxide-free environment. 缺二氧化碳的環(huán)境
D) an environment filled with the greenhouse gas
充滿了溫室氣體的環(huán)境
分析：標準的細節(jié)題，要想得到答案只有繼續(xù)閱讀文章。
第2段：
Previously（以前）, researchers had thought （曾經(jīng)認為）that it was impossible（不可能的） for plants to make significant（有意義的、重要的） amounts（數(shù)量） of the gas. They had assumed that microbes（微生物） need to be in（在。。。之中） environments without （沒有）oxygen（氧氣） 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（吸收熱量） in Earth’s atmosphere（大氣層）and contribute to（導致、引起）global warming（全球變暖）.
結(jié)論：事實上，這一段仍然在回答第一題。從側(cè)面我們也可以更加確定剛才的答案是正確的。還是要注意所有動詞的時態(tài)！我們并未找到第二題答案，因此繼續(xù)！
第三段：
2>. In its experiments（實驗）, Keppler’s team used（使用） sealed（原形seal，密封） chambers (室，房間) that（引導定語從句） contained（包含、包括） the same concentration（密度） of oxygen that（引導定語從句， 修飾concentration） Earth’s atmosphere（大氣、大氣層） has. They measured （測量、衡量）the amounts（數(shù)量） of methane that（引導定語從句， 修飾the amounts） were released（釋放） by both living plants（活著的植物） and dried（干的） plant material（材料）, such as fallen leaves（落葉）.
結(jié)論：開頭的第一句就揭示了答案應(yīng)該是B。
5．看第3題：
3. Which statement is true of the methane emissions of plants in the experiment?
在實驗中，有關(guān)植物釋放沼氣的陳述，哪一個是正確的？
A) The lower the temperature, the higher the amount of methane emissions.
溫度越低，沼氣的釋放量越高。
B) Living plants release less methane than dried plants at the same temperature.
在相同的溫度下，活著的植物要比干植物釋放的沼氣少。
C) When exposed to sunlight, plants stop releasing methane.
當植物暴露于陽光之下時，就停止釋放沼氣。
D) The higher the temperature, the greater the amount of methane emissions.
溫度越高，沼氣的釋放量越高。
分析：這道題中有三個關(guān)鍵詞：methane emissions，Living plants，dried plants。因此要得出答案，必須讀4，5兩段。
讀第四段：
With（至于） the dried plants, the researchers took measurement（進行測量） at temperatures（溫度） ranging from （從。。。范圍到。。。范圍）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（多達）3 nanograms（微克） of methane per hour（每小時）. (One nanogram is a billionth（十億分之一） of a gram.) With every 10-degree（度） rise（上升） in temperature, the amount of methane released each hour roughly（大約）doubled（兩倍）.
第五段：
Living plants growing at their normal（正常的） temperatures released as much as（像。。。一樣多） 370 nanograms of methane per gram of plant tissue（每一克的植物組織） per hour. Methane emissions（散發(fā)，發(fā)射）tripled（增加三倍；） when living and dead plant was exposed to（暴露于。。。之下） sunlight.
結(jié)論：這道題要答對，這兩段一定要全部看懂。我們可以得出結(jié)論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于干植物的釋放量，在陽光下，它們的沼氣釋放量是正常情況的三倍。因此D是正確答案。
6．看第四題：
What of the following about methane is Not mentioned in the passage?
下列關(guān)于沼氣的內(nèi)容哪一個沒有在文章中被提到？
A) Plants growing in soil release methane.在土壤中生長的植物釋放沼氣。
B) Plants growing in water release methane. 在水中生長的植物釋放沼氣。
C) Soil microbes consume methane.土壤微生物消耗沼氣。
D) Microbes in plants produce methane.植物中的微生物產(chǎn)生沼氣。
讀第6段：
Because there was plenty of （足夠的、充足的）oxygen available（可以得到的）, it’s unlikely（不可能的） that the types（種類） of bacteria（bacterium的復數(shù)，細菌） that（引導定語從句） normally（正常地） make methane were involved（被涉及，包含）. Experiments on plants that（引導定語從句， 修飾plants） were grown in water rather than（而不是） soil also resulted in （引起、導致，同義詞cause, contribute to）methane emissions. That’s another strong sign(跡象) that（引導的是同位語從句，對sign進行具體的解釋，說明）4>. the gas came from the plants and not soil microbes（氣體產(chǎn)生于植物并不是土壤微生物。）.
結(jié)論：通過閱讀這一段，分析得出答案D的表述與原文是不吻合的，因此選擇D。
7．看第五題：
What is the beneficial point of some microbes consuming plant-produced methane?
一些微生物在消耗由植物產(chǎn)生的沼氣時有什么好處？
A) Methane becomes less poisonous.沼氣的毒性減少。
B) Methane is turned into a fertilizer. 沼氣被轉(zhuǎn)化成肥料。
C) Less methane reaches the atmosphere.到達大氣中的沼氣會減少。
D) Air becomes cleaner.空氣變得更干凈了。
最后一段：
The new finding（發(fā)現(xiàn)） is an “interesting observation（觀察）,” says Jennifer Y. King, a biogeochemist（生物地球化學家） at the University of Minnesota in St. Paul.
5>. Because some types（種類） of soil microbes consume（消耗） methane, they may prevent（阻止某事的發(fā)生） plant-produced methane from reaching（到達） the atmosphere. Field (土地)tests will be needed to assess（確定、估計） the plant’s influence（影響）, she notes.
結(jié)論：很容易得到答案是C。