51．Details of the private life of an astronaut are hard to come by，because they are＿＿＿．
　　[A]his own business and privacy
　　[B]secrets as far as interviews are concerned
　　[C]the property of an American magazine
　　[D]the first—rate national confidential information
　　52．To audience，the typical American astronaut＿＿＿．
　　[A]has a limited vocabulary
　　[B]is a clean—cut，cheerful and frank guy
　　[C]can’t understand a sophisticated joke 
　　[D]is well-built but rather slow—witted
　　53．In politics，astronauts are generally＿＿＿．
　　[A]democrats
　　[B]republicans 
　　[C]conservatives 
　　[D]communists
　　54．The phrase“talking shop”(Line 4，Para．6)probably means＿＿＿．
　　[A]talking about shopping 
　　[B]discussing one’s work with colleagues
　　[C]exchanging personal news 
　　[D]talking with friends in a group
　　55．Which of the statements is NOT true?
　　[A]Astronauts have a good job which demands high．
　　[B]The divorce rate in NASA is very low．
　　[C]The NASA astronauts mostly find friends from among their work．
　　[D]There is no younger man in his twenties in the spaceship．

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