May I have a ____________? Sure, here you are. [ ]
A. see
B. school
C. look
答案:C
其分子结构中具有氧环的是
A.小檗碱B.麻黄碱C.伪麻黄碱D.东莨菪碱E.山莨菪碱
什么是阻火器?它有何特点?