[填空题]The Capital Airport has been in use for 20 years.
The Capital Airport was built ______.

[填空题]The Capital Airport has been in use for 20 years． The Capital Airport was built ______.

[填空题]The Capital Airport has been in use for 20 years.
The Capital Airport was built ______.

[单项选择]A. The strategy for airport security has been far from perfect.
B. The equipments and system of airport security are very old.
C. The officers of airport security are unskilled to deal with criminals.
D. The technology alone is not enough to identify vicious intentions.

[填空题]The Capital Airport is the largest one in China． The Capital Airport is ______ any other airport in China．

[填空题]The Capital Airport is the largest one in China.
The Capital Airport is ______ any other airport in China.

[单项选择]

No other capital in Europe has more charm(迷人) or a richer past than Vienna, the capital of Austria. Green woods, mountains, and the large Danube River give the city beautiful surroundings.
Vienna has more than 1 600 000 people. Almost one-fourth of all the people of Austria live there. Vienna is sometimes called "a city without a country". It is so big that it does not seem to be suitable (适合的) in so small a country as Austria.
Vienna was a center of science and art and music, too. Many great musicians lived there. It had the name of being a city of spirits, partly because of the dance music and operettas(轻歌剧) written by Viennese musicians.
After World War I, Vienna found itself the capital of a rather poor country of less than 7 000 000 people. World War Ⅱ made Vienna even worse than it was before. Since 1955, however, Vienna has been fast regaining its past greatness.

According to the passage, Vienna was once a center of （　）.
A. traffic
B. trade and science
C. art and music
D. [b]and[c]