选出正确答案.
(    )（1）这是一张美国地图。
A.    Here is a map of the United States.
B. Here is the United States.
(   )（2）这是美国的首都。
A.    This is the capital city of the U.S.
B.     This is the United States.
(   )（3）首都是华盛顿。
A. The city is Washington.，D. C.
B. The capital city is Washington，D. C.