The other day we traveled fifteen hours to a magic country. which     America,and we enjoyed ourselves

there for a month. [ ]

A. was called      

B. is called        

C. had been called      

D. has been called

制冷机运行时用（）冷却氟利昂，氟利昂冷却乙二醇。

A.冷却循环水

B.氟利昂

C.铵

D.油