莽草酸可用于合成药物达菲,其结构简式如图,下列关于莽草酸的说法正确的是 ( ) A.分子式为C7H6O5 B.分子中含有两种官能团 C.可发生加成和取代反应 D.在水溶液中羟基和羧基均能电离出氢离子 答案:C Don’t believe in those ads that you can master a language in one month. Instead, it is a(n) _______process, which may last for years. A. rapid B. instant C. gradual D. regular