单项选择题
A.a/(a+b)与c/(c+d) B.a/(a+c)与d/(b+d) C.a/c与b/d D.b/(a+b)与d/(c+d) E.a/(a+d)与c/(c+d)
A.杂醇油 B.甲醇 C.乙醇 D.甲醛 E.展青霉毒素