题目

 Professor Yang gave all the textbooks to all the pupils, except ________ who had already taken them. A. these B. ones C. the ones D. the others 答案：C将面团包在纱布中放在清水中搓洗，请你用试剂检测黏留在纱布上的黏稠物质和洗出的   白浆物质，所用试剂分别为 A．碘液、苏丹III染液 B．双缩脲试剂、碘液 C．碘液、斐林试剂 D．双缩脲试剂、斐林试剂