Against the supposition that forest fires in Alaska, Canada and Siberia warm the climate, scientists have discovered that cooling may occur in areas where burnt trees allow more snow to mirror more sunlight into space.

This finding suggests that taking steps to prevent northern forest fires to limit the release of greenhouse gases may warm the climate in northern regions. Usually large fires destroyed forests in these areas over the past decade. Scientists predict that with climate warming, fires may occur more frequently over the next several centuries as a result of a longer fire season. Sunlight taken in by the earth tends to cause warming, while heat mirrored back into space tends to cause cooling.

This is the first study to analyze all aspects of how northern fires influence climate. Earlier studies by other scientists have suggested that fire in northern regions speed up climate warming because greenhouse gases from burning trees and plants are released into the atmosphere and thus trap heat.

Scientists found that right after the fire, large amounts of greenhouse gases entered the atmosphere and caused warming. Ozone（臭氧） levels increased, and ash from the fire fell on far-off sea ice, darkening the surface and causing more radiation from the sun to be taken in. The following spring, however, the land within the area of the fire was brighter than before the fire, because fewer trees covered the ground. Snow on the ground mirrored more sunlight back into space, leading to cooling.

“We need to find out all possible ways to reduce the growth of greenhouse gases in the atmosphere.” Scientists tracked the change in the amount of radiation entering and leaving the climate system as a result of the fire, and found a measurement closely related to the global air temperature. Typically, fire in northern regions occurs in the same area every 80 to 150 years. Scientists, however, found that when fire occurs more frequently, more radiation is lost from the earth and cooling results. Specifically, they determined when fire returns 20 years earlier than predicted, 0.5 watts per square meter of area burned are soaked up by the earth from greenhouse gases, but 0.9 watts per square meter will be sent back into space. The net effect is cooling. Watts are used to measure the rate at which energy is gained or lost from the earth.

1.．According to the new findings, taking steps to prevent northern forest fires may __________.

2.．The following are all the immediate effects after a forest fire EXCEPT __________.

3.．Earlier studies about northern forest fires __________.

4.．The underlined phrase “soak up” in the last paragraph most probably means __________.

5.．From the passage we can draw a conclusion that forest fires in Alaska, Canada and Siberia may ____.

All too often , a choice that seems sustainable（可持续的）turns out on closer examination to be problematic. Probably the best example is the rush to produce ethanol（乙醇）for fuel from corn . Corn is a renewable resource —you can harvest it and grow more, almost limitlessly. So replacing gas with corn ethanol seems like a great idea .

One might get a bit more energy out of the ethanol than that used to make it, which could still make ethanol more sustainable than gas generally, but that’s not the end of the problem. Using corn to make ethanol means less corn is left to feed animals and people, which drives up the cost of food. That result leads to turning the fallow land — including, in some cases, rain forest in places such as Brazil — into farmland, which in turn gives off lots of carbon dioxide（CO₂）into the air. Finally, over many years, the energy benefit from burning ethanol would make up for the forest loss. But by then, climate change would have progressed so far that it might not help.

You cannot really declare any practice “sustainable” until you have done a complete lift-cycle analysis of its environmental（环境的）costs. Even then, technology and public policy keep developing, and that development can lead to unforeseen and undesired results. The admirable goal of living sustainable requires plenty of thought on an ongoing basis.

1.What might directly cause the loss of the forest according to the text?

A. The growing demand for energy to make ethanol.

B. The increasing carbon dioxide in the air.

C. The greater need for farmland.

D. The big change in weather.

2.The underline word “it” in the second paragraph refers to “              ” .

A. the energy benefit               B. the forest loss

C. climate change                  D. burning ethanol

3.The author thinks that replacing gas with corn ethanol is               .

A. impractical   B. acceptable    C. admirable    D. useless

4.What does the author mainly discuss in the text?

A. Technology.                   B. Sustainability.

C. Ethanol energy.                D. Environmental protection.

完形填空（共20小题；每小题1.5分，满分30分）
Once upon a time, there was a boy who would go into the forest and gather food and herbal medicines(草药) with some of his fellows every spring. However, one year, a tiger  36  in the forest and no one dared go into the forest again. One day, the boy’s father became  37 ， and the family couldn’t afford the  38  that the father needed. The boy decided to try and find some herbal medicines as well as some food in the forest.
It was a perfect sunny day. At first, it was quiet and  39  happened. But later, when the boy bent down to reach one more mushroom, he was suddenly pushed to the ground. A large shadow 40   him. He rolled over and looked  41  in shock as the tiger said in a deep voice. “You are my  42  . Say good-bye to this world.”  43  his sick father, the boy knew he couldn’t die. He quickly calmed down and put a(n)  44  into his mouth, and chewed and swallowed.Then he said, “45  you can kill and eat me, but I  46  you to know that these mushrooms are  47  poisonous(有毒的). You can eat me,  48  you will die too. My family will  49 me and find you. They will  50 your stomach and eat your meat. Your fine  51 will carpet the floor of a rich man’s house and your tiger bones will get a good  52  in the medicine shops. My family will have enough for a year or more and I will be given a good funeral（葬礼） and long53  .
The tiger hesistated. He saw the frightful mushrooms in the basket and  54  his appetite(胃口). He slowly walked away. The boy saved his own life with his quick  55 .
36.  A．broke out        B. woke up       C. showed up         D. set out
37．A．hungry          B. ill            C. angry            D. mad
38．A．love               B. medicine       C. care            D. doctors
39．A．anything          B. everything      C. nothing          D. something
40．A．covered           B. followed          C. caught          D. pushed
41．A．down           B. out              C. around            D. up
42．A．energy          B. power          C. enemy          D. supper
43．A．Looking after   B. Thinking of     C. Bringing back    D. apple
45.  A .Of course      B. No way       C. In the beginning    D. In any case
46．A．choose             B. wish            C. persuade       D. order
47．A．expensive          B. delicious       C. deadly            D. magic
48．A．as             B. so             C. but             D. because
49．A．look for           B. call for        C. take care of    D. get rid of
50．A．feed            B. open            C. sell              D. kick
51．A．head           B. tail             C. paws           D. skin
52．A．price            B. seller            C. reward           D. doctor
53 A．understood       B. encouraged     C. needed         D. remembered
54．A．lost            B. increased        C. regained       D. forgot
55．A．skill           B. warning        C. thinking        D. word

 Against the assumption that forest fires in Alaska, Canada and Siberia warm the climate, scientists have discovered that cooling may occur in areas where burnt trees allow more snow to mirror more sunlight into space.

         This finding suggests that taking steps to prevent northern forest fires to limit the release of greenhouse gases may warm the climate in northern regions. Usually large fires destroyed forests in these areas over the past decade. Scientists predict that with climate warming, fires may occur more frequently over next several centuries as a result of a longer fire season. Sunlight taken in by the earth tends to cause warming, while heat mirrored back into space tends to cause cooling.

         This is the first study to analyze all aspects of how northern fires influence climate. Earlier studies by other scientists have suggested that fire in northern regions speed up climate warming because greenhouse gases from burning trees and plants are released into the atmosphere and thus trap heat.

         Scientists found that right after the fire, large amounts of greenhouse gases entered the atmosphere and caused warming. Ozone（臭氧）levels increased, and ash from the fire fell on far-off sea ice, darkening the surface and causing more radiation from the sun to be taken in. The following spring, however, the land within the area of the fire was brighter than before the fire, because fewer trees covered the ground. Snow on the ground mirrored more sunlight back into space, leading to cooling.

         “We need to find out all possible ways to reduce the growth of greenhouse gases in the atmosphere.” Scientists tracked the change in amount of radiation entering and leaving the climate system as a result of the fire, and found a measurement closely related to the global air temperature. Typically, fire in northern regions occurs in the same area every 80 to 150 years. Scientists, however, found that when fire occurs more frequently, more radiation is lost from the earth and cooling results. Specifically, they determined when fire returns 20 years earlier than predicated, 0.5 watts per square meter of area burned are soaked up by the earth from greenhouse gases, but 0.9 watts per square meter will be sent back into space. The net effect is cooling. Watts are used to measure the rate at which energy is gained or lost from the earth.

1.According to the new findings, taking steps to prevent northern forest fires may _______.

   A. result in a warming climate         

B. cause the forest fires to occur more frequently

   C. lead to a longer fire season                             

D. protect the forests and the environment there

2.Earlier studies about northern forest fires ________.

   A. analyze all aspects of how northern fires influence climate

   B. indicate that forest fires will pollute the atmosphere

   C. suggest that people should take measures to protect environment

   D. suggest that the fires will speed up climate warming

3.The underlined phrase “soaked up” in the last paragraph most probably means ________.

         A. released          B. absorbed            C. created               D. disturbed

4. From the text we can draw a conclusion that forest fires in Alaska, Canada and Siberia may ______.

         A. warm the climate as the assumption goes

         B. allow more snow to reflect more sunlight into space and thus cool the climate

         C. destroy large areas of forests and pollute the far-off sea ice

         D. help to gain more energy rather than release more energy .

Once an Englishman named Larry Belmont went to Russia for a holiday. After he got back some of his friends came. “I had a very dangerous trip while I was in Russia.” Larry said, “I went to see a friend in the country and when the sun went down, I was still traveling through a forest in a sleigh(雪橇). It was a long way from my friend’s house when about twenty wolves began to follow my sleigh.”

“It was very dark in the forest. There was thick snow on the ground. First I heard the wolves. The noise was terrible! Then I saw long, grey forms among the trees, and soon the wolves were near me. They were running very fast, and they didn’t seem to get tired like the horses.”

“What did you do?” one of Larry’s friends asked.

“When the wolves got very near,” Larry answered, “I put up my gun and shot the first wolf dead. Then all the other wolves stopped and ate it, so my sleigh got away from them for a few minutes. Then they finished their meal, and I heard them coming again. The moon was shining brightly on the snow now, and after a few minutes I saw them running among the trees once more. They came nearer again, and then I shot another one of them, and the others stopped once more to eat it. The same thing happened again, and my horses become more and more tired and ran slower and slower until, after two hours, only one wolf was still alive and following me.”

“Wasn’t it too fat to run?” one of Larry’s friends asked.

1.The purpose of this passage is to ______.

A. amuse readers                B. tell an exciting adventure

C. praise Larry Belmont’s bravery  D. show the danger of traveling through a forest

2.According to what Larry said, the last wolf _______.

A. was the strongest of all              B. had eaten up all the other wolves

C. ran much faster than the other wolves  D. was very fat and couldn’t run fast enough

3.From what Larry’s friend asked at the end, we know that_______.

A. Larry’s trip was really dangerous    

B. the last wolf was too fat to run

C. all the wolves had been shot by Larry

D. the friend did not believe what Larry had said