第14题: [单项选择]生活饮用水卫生标准规定,用氯消毒时 A. 接触1~2h,游离性余氯不低于1mg/L。 B. 接触1~2h,游离性余氯不低于0.5mg/L C. 接触30min,游离性余氯不低于0.5mg/L D. 接触30min,游离性余氯不低于0.3mg/L E. 接触30min,游离性余氯不低于1mg/L 参考答案:D
第21题: [单项选择]Passage Two Questions 30 to 32 are based on the passage you have just heard. A. Many students try to study the whole night before an exam. B. Sleep may improve memory. C. Exams may harm memory. D. Sleep can improve listening ability. 参考答案:B 答案解析:[听力原文]30-32 Many students try to study the whole night and do not sleep before an exam. Two s