题目

While traveling abroad, Mr. Jackson Frank ran short of money. So he wrote to his brother, asking for $500. “Send the money by telegram,” he wrote, “to the Fisher Bank in P...”After a week he began calling at the Fisher Bank. He showed his passport. “ Nothing has come for you,” he was told. This went on for two weeks and Mr. Frank got very worried. He sent a telegram to his brother， but there was no reply. In the fourth week Mr. Frank was arrested for failing to pay his hotel bill. His passport was taken from him. He tried to explain the problem, but no one believed him. He was许多科学家认为，与现在的大气成分相比，原始大气中不含的物质是（ ）A.甲烷B.氢C.氧气D.水蒸气