The research of Till Von Wachther suggests that in recession graduates from elite universities tend to _____.
Questions 21 to 25 are based on the following passage.
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.
Your network consists of a single Active Directory domain. All servers run Windows Server 2003 Service
Pack 2 (SP2).
You have two global groups named Research and ResearchManagers. The Research group contains all users in a department named Research. The ResearchManagers group contains all managers in the Research department. All members of the ResearchManagers group are members of the Research group.
You create a shared folder named Research. The permissions for the Research share are shown in the exhibit.(Click the Exhibit button.)
You need to modify the share permissions to ensure that only members of the ResearchManagers group can add and modify files over the network.
What should you do? ()
免费的网站请分享给朋友吧