第一节（共15小题，每小题2分，共30分）
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。
A
The National Gallery of Art in Washington, D.C., is one of the world's greatest art museums. Millions of people have entered its doors to see paintings by the world's fine artists. But if these priceless masterpieces are to be preserved, the Gallery must protect them carefully. The Gallery's 135-man guard force has successfully prevented them from being stolen, but protecting the paintings from nature is a greater problem.
