[解析]
(1)B 细节题.根据The basic flag of the untied states is one of the world's oldest national flags可知美国的基本旗帜是世界上最古老的国旗之一,结合选项,答案为B.
(2)D.推理题.根据The first official flag of the United States was created by Congress on June 14,1777可知国旗创立于1777年7月,在美国独立战争期间(1776﹣1783),即答案为D.
(3)B 细节题.根据It consisted of 13 alternate red white stripes and 13 white stars in a field of blue,representing the 13 colonies that had declared their independence in 1776可知,美国的国旗由13条红白相间条纹和13颗星星组成,代表着在1776年独立的13个殖民地,结合选,答案为B.
(4)D 细节题.根据文章内容,By 1817,there were 20 states in the Union,and it became apparent that adding one stripe for each new state would destroy the shape of the flag.As a result,Congress in 1818 restored the original design of 13 stripes and provided that each state was to be represented by one star.到了1817年的时候,有20个州了,如果每添一个新的州都加一个新的条纹的话,就会破坏国旗的形状了,因此,国会在1818年才决定了新的州由星星代替,只保留最开始的13个独立的殖民地的条纹.结合选项,故选D