题目

乳糖是一种二糖，可以水解生成葡萄糖和半乳糖。半乳糖和葡萄糖互为同分异构体，则乳糖的分子式为(    ) A.C6H12O6                                         B.C18H30O15 C.C12H24O12                           D.C12O22O11 答案：D 解析:同分异构体分子式相同，所以半乳糖为C6H12O6乳糖+H2OC6H12O6+C6H12O6 由质量守恒乳糖分子式为C12H22O11If we expect ________ much cleaner world, we should attract ________ world's attention to protect it. [     ] A. a; a  B. a ; 不填    C. a; the  D. the; 不填