单选题 Why is Washington, D.C. the most important American city? [A] It is the capital of the United States. [B] It is the largest in population. [C] It is the must beautiful city.

【正确答案】 A

【答案解析】[精解] 题干的意思是为什么华盛顿特区是美国最重要的城市。A的意思是它是美国首都，B的意思是它人口最多，C的意思是它是最漂亮的城市。文中最后一句"The most important city in the United States is Washington，D．C．It is the capital，but it is much smaller than New York．”，即美国最重要的城市是华盛顿特区，它是首都，虽然它比纽约小很多。因此正确答案为A。