I. 单词拼写（共10小题，每小题1分；满分10分）
根据所给汉语提示用适当的单词完成句子。（每空只写一个单词）
71. He was holding his ______（呼吸）while seeing the horrible movie.
72. It is a scientists’ job to ______（寻求）the truth about the Big Bang of the universe.
73. I am not as lucky as you. On the ______（相反），I failed in the exam.
74. The proof is not ______（令人信服的）; people don’t believe UFO.
