题目

The ____________ of printing helped to spread the knowledge.A. result B. experience C. invention D. reason 答案：【答案】C【解析】句意：印刷术的发明有助于传播知识．考查名词的词义辨析。分析句子，结合选项，推测意思是印刷术的发明有助于传播知识．A. result结果；B. experience经历；C. invention发明；D. reason原因。故选C．把30缩小到原来的　 　是0.03．