题目

双缩脲的分子式是H2NOC－NH－CONH2，利用鉴定双缩脲的试剂来鉴定蛋白质，是由于蛋白质分子中含有(   ) A．肽键    B．氨基酸    C．羧基    D．氨基   答案：A 蛋白质的肽键“－NH－CO－”与双缩脲类似。—We decided 　　　　 Jack to take part in the competition.—I couldn’t agree more. He studies 　　　　 and he is also the cleverest in his class.A．to send; most hardlyB．send; most hardlyC．to send; hardestD．send; hardest