题目

—It's many years since I saw you last; I ______ you at all.—I wouldn't have, either, if someone ______ you by the name. A . haven't recognized; didn't call B . didn't recognize; didn't call C . didn't recognize; hadn't called D . recognized; had called 答案：C9．分子式为C5H12O属于醇且能催化氧化成醛的有机物同分异构体的数目是（　　）A．2种B．3种C．4种D．5种