题目内容
Lead deposits, which accumulated in soil and snow during the 1960’s and 70’s, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.
A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining.
In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate (区分) the lead sources. The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States.
In a study published in the journal Ambio, scientists found that lead levels in soil in the Northeastern United States had decreased markedly since the introduction of unleaded gasoline.
Many scientists had believed that the lead would stay in soil and snow for a longer period.
The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990. The forest environment processed and redistributed the lead faster than the scientists had expected.
Scientists say both studies demonstrate that certain parts of the ecosystem (生态系统) respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.
69. The study published in the journal Nature indicates that ________.
A. the Clean Air Act has not produced the desired results
B. lead deposits in arctic snow are on the increase
C. lead will stay in soil and snow longer than expected
D. the US is the major source of lead pollution in arctic snow
70. Lead accumulation worldwide decreased significantly after the use of unleaded gas in the US _____ .
A. was discouraged B. was enforced by law
C. was prohibited by law D. was introduced
71. How did scientists discover the source of lead pollution in Greenland?
A. By analyzing the data published in journals like Nature and Ambio.
B. By observing the lead accumulations in different parts of the arctic area..
C. By studying the chemical elements of soil and snow in Northeastern America.
D. By comparing the chemical compositions of leaded gasoline used in various countries.
72. The authors of the Ambio study have found that ________.
A. forests get rid of lead pollution faster than expected
B. lead accumulations in forests are more difficult to deal with
C. lead deposits are widely distributed in the forests of the US
D. the upper layers of soil in forests are easily polluted by lead emissions
69-72.
It was the second day of a winter holiday in Queenstown, New Zealand, three years ago. When we decided to explore the beautiful scenery, our landlady 36 us,“Make sure you are well wrapped up today. The weather is 37 . Head back when you see snowfall.”
The day was bright and sunny, and I started to wonder if she was being too cautious. When snow began to fall at 6:00 pm, I was not worried, thinking we’d have no 38 in catching a taxi back. However, we waited for a while, and all the drivers shook their heads when told of our 39 .
The first driver passed by and gave me a card with a number for me to 40 help. I was filled with 41 , but I had no choice but to lead my three sisters to a nearby place to make the 42 . Then a taxi drew up and we climbed in. The driver did not appear very friendly. Then the light streaming from his headlights showed very 43 why no taxi wanted to take us to our hotel. And I began to understand the driver’s apparently unfriendly silence — he was worried. The steep incline (斜坡) ahead was 44 with snow. The taxi slowly made its way up the hill. Suddenly, we came to a dead stop, and the driver turned to us. “Look! It is very 45 to go forward. You have to get out and walk. If I drive any further, the taxi will slide back,” he said. “Er ... can you keep your headlight on and help my elder sister? The rest of us will follow you up,” I said. The driver 46 .
We made it safely back to our hotel. Even though it 47 for the rest of the days, we could see the silver lining in the cloud(一线希望): the generous soul who helped us.
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Justin’s bedroom was so full of flat bicycle tires, bent tennis rackets, deflated(瘪掉的)basketballs, and games with missing pieces that you could barely get in the door. His parents pleaded with him to clean out his room.
“What use is a fish tank with a hole in the bottom?” his father asked. But Justin simply smiled and repeated his motto, “Never throw anything out, you never know when it might come in handy.”
When Justin was away from home, he always carried his blue backpack--a smaller version of his bedroom--a place to store the many objects that he collected. It was so worn and stretched that it hardly resembled a backpack anymore.
Justin had earned a reputation for figuring things out and getting people out of otherwise hopeless situations. Many of his classmates and neighbors sought him out when they needed help with a problem. On the first day of school, his friend Kenny, came looking for Justin.
“Do you think you have something in your bag that could help me remember my locker combination?” he asked. “I lost the piece of paper it was written on. I have a science class in two minutes and if I’m late on the first day it’ll make me look bad for the rest of the year.” Kenny looked really worried.
“Relax,” Justin said, taking his backpack off and unzipping the top. “Remember how you borrowed my notebook in homeroom to write the combination down? Well, I know how we can recover what you wrote.”
He took the notebook and a soft lead pencil out of his bag. The page that Kenny had written on had left faint marks on another page in the notebook. Justin held the pencil on its side and rubbed it lightly over the marks. Slowly but surely the numbers of the locker combination appeared in white, set off by the gray pencil rubbings.
“That’s amazing!” Kenny said. “I owe you one.” And he dashed off to open his locker.
It was just another day in the life of the boy whose motto was “Never throw anything out, you never know when it might come in handy.”
【小题1】Why is Justin’s room such a mess? WWW.K**S*858$$U.COM
A.He always forgets to clean it. | B.He shares the room with his brother. |
C.He has no time to clean it. | D.He never throws anything away. |
A.He uses it as a place to store objects. |
B.He uses it to carry his books and sports equipment. |
C.His parents tell him to clean it all the time. |
D.He’s had it for as long as he can remember. |
A.ignored | B.asked | C.pushed | D.Ordered |
A.Annoyed. | B.Disinterested. | C.Grateful. | D.Angry. |