iate (区分) the lead sour ___s. The dominant lead ratio found in Greenland snow ___tched 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 North-eastern United States had decreased ___rkedly sin ___ 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 enviro ___ent pro ___ssed and redistributed the lead faster than the scientists had expected. Scientists say both stu ___s demonstrate that ___rtain 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 li ___nse to pollute.
26. The study published in the journal Nature indicates that ____. A) lead deposits in arctic snow are on the increase B) the Clean Air Act has not produ
___d the desired results C) the US is the ___jor sour ___ of lead pollution in arctic snow D) lead will stay in soil and snow longer than expected 27. Lead aumulation worldwide decreased significantly after the use of unleaded gas in the US ____. A) was introdu ___d B) was discouraged C) was prohibited by law D) was enfor ___d by law 28. How did scientists discover the sour ___ of lead pollution in Greenland? A) By ___yzing the data published in journals like Nature and Ambio. B) By studying the chemical elements of soil and snow in Northeastern America. C) By paring the chemical positions of leaded gasoline used in various countries. D) By observing the lead aumulations in different parts of the arctic area. 29. The authors of the Ambio study have found that ____. A) forests get rid of lead pollution faster than expected B) lead deposits are widely distributed in the forests of the US C) lead aumulations in forests are more difficult to deal with D) the upper layers of soil in forests are&n
bsp;easily polluted by lead emissions 30. It can be inferred from the last paragraph that scientists ____. A)
lack sufficient means to bat lead pollution B) still consider lead pollution a problem C) feel relieved by the use of unleaded gasoline D) are puzzled by the mystery of forest pollution
Part III Vocabulary (20 minutes)
Directions: There are 30 inplete senten ___s in this part. For each senten ___ there are four choi ___s ___rked A), B), C) and D)。 Choose the ONE answer that best pletes the senten ___. Then ___rk the corresponding letter on the Answer Sheet with a single line through the ___ntre.
31. Salaries for ____ positions seem to be higher than for per ___nent ones. A) temporary B) voluntary C) optional D) legal 32. Mrs. Smith was so ____about everything that no servants could please her. A) precise B) particular C) specific D) special 33. His temper and personality show that he c
an bee a sol ___r of the top ____. A) circle B) category C) grade D) rank 34. There has been a collision ____a
number of cars on the ___in road to town. A) engaging B) posing C) involving D) consisting 35. Nor ___n Davis will be remembered by ___ny with ____not only as a great scholar but also as a most delightful and faithful friend. A) friendliness B) affection C) kindness D) warmth 36. Scien ___ and technology have ____in important ways to the improvement of agricultural production. A) witnessed B) assisted C) attached D) contributed 37. He never arrives on time and my ____is that he feels the meetings are useless. A) conferen ___ B) inferen ___ C) preferen ___ D) referen ___ 38. Only those who can ____to lose their money should ___ke
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