A:乙烯的结构简式CH2=CH2
B:甲烷的结构式 CH4
C:Mg原子结构示意图
D:H原子的电子式 H+
— did she go last Sunday?
— She went to a farm.
若a5=b7=c8,且3a﹣2b+c=3,则2a+4b﹣3c的值是( )