2005年1月大学英语四级考试试题

A) was discouraged                         B) was enforced by law

C) was prohibited by law                     D) was introduced

23. 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.

24. 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