Passage Two
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 Uni
A. By analyzing the data published in journals like Nature.
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.
Passage Two
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 Uni
A. the Clean Air Act has not produced the desired results
B. lead deposits in arctic snow arc on the increase
C. lead will stay in soil and snow longer than expected
D. the U. S. is the major source of lead pollution in arctic snow
| Lead deposits, which accumulated in
soil and snow during the 1960’s and 1970’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 world-wide 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 A. was introduced B. was discouraged C. was prohibited by law D. was enforced by law 我来回答: 提交
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