题目

某烃分子中含有一个双键和一个三键，则它的分子式可能是(    )A.C4H6                  B.C5H6               C.C7H8                  D.C10H8 答案：解析：烃的分子式应符合通式CnH2n-4，应选B。答案：B—It is said that _____ the young people may lose their abilities to hear after five years if they listen to MP4 players which are too loud for more than five hours a week.A. thousand of B. six thousand C. six thousand of