问题
单项选择题 A型题
既提高轴向分辨力又提高横向分辨力的措施是（）。
A.缩短脉冲长度
B.使声束变细
C.增大声束宽度
D.提高探头频率
E.降低探头频率
答案
参考答案：D
解析：提高探头频率使声波的波长缩短，轴向分辨力得到提高；同时使声束变细，横向分辨力也得到提高。
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既提高轴向分辨力又提高横向分辨力的措施是（）。
A.缩短脉冲长度
B.使声束变细
C.增大声束宽度
D.提高探头频率
E.降低探头频率
参考答案：D
解析：提高探头频率使声波的波长缩短，轴向分辨力得到提高；同时使声束变细，横向分辨力也得到提高。
Brazil is the greatest football nation in the world. There are 170 million Brazilians. How many of them are football fans? 100 million! All of them think they know all about football. This makes life very difficult for the Brazilian team managers. When things go bad for the Brazilian team, the newspapers would demand that the team manager should leave his job. “If we win, they me in heaven,” a manager once said. “If we lose, they put me in hell(地狱).” You can’t escape football in Brazil. There are football matches on every street and beach. On television, the results of football matches come before the main news programs. There are six television channels(频道) in Rio de Janeiro. On Sundays each channel shows a different football match. Brazil is not the richest country in the world, but the government spends lots of money on football. It cost more than one billion pounds to prepare for the 1978 World Cup. That’s 10 pounds for every Brazilian man, woman, and child. And many Brazilians don’t earn as much as 10 pounds a week. Is it worth it? “Brazil must have a great football team,” says one journalist. “If it costs one billion pounds, that’s all right. If the government doesn’t give us a good team, then it will become unpopular. Football is more than a game in Brazil.” Football is more than a game in Brazil. This is certainly true in its largest city, Sao Paulo. The most popular team is Corinthians. Corinthians’ fans are the most loyal and emotional in Brazil. When Corinthians win, production(产量) in the Sao Paulo car factories increases by fifteen per cent. When they loses, it drops. At one time Corinthians won the national championship for the first time, for four days fans danced and sang in the streets, Why are people so loyal to one football team? What makes a football fan? One man says, “Without Corinthians my life would be sad. Corinthians bring some joy and excitement into my life. We all need that, don’t we?” 小题1:In Paragraph 1, what the manager said means_______. A, he is respected by newspapers B,. he will probably be killed by fans C. he is judged on his team’s results D. it’s difficult for him to get good scores 小题2:All the following statements about the Brazilians and football are true EXCEPT _______.
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