下列物质中不能与2，4-二硝基苯肼试剂产生黄色沉淀的是( )。
A．丙醛
B．正丙醇
C．苯甲醛
D．丙酮
参考答案：B
结核病转向愈合时的改变为
A．钙化
B．吸收消散
C．纤维化和纤维包裹
D．病灶周围炎并继发干酪样坏死
开放作文。
请根据下面提示，写一篇短文。词数不少于50。
In your spoken English class, your teacher shows you the following picture You are asked to describe
the picture and explain how you understand it.
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