根据材料请回答 16～22 SmokingSince 1939, numerous studies have been conducted to determ根据

材料请回答 16～22 Smoking Since 1939, numerous studies have been conducted to determine whether smoking is a health hazard.The trend of the evidence has been consistent and indicates that there is a serious health risk.Research teams have conducted studies that show beyond all reasona-ble doubt that tobacco smoking is associated with a shortened life expectancy （）And low tar tobacco are claimed to make smoking to some extent sa-fer, but they can only slightly reduce,not eliminate,the hazards． 第 16 题 It is easy to determine whether smoking is hazardous． A．RightB．WrongC．Not mentioned