第4题: [单项选择]When a machine analyses the frequencies used by a particular voice and draws a graph of them, sound is ______ electronically into a pattern of lines. A. relieved B. converted C. magnified D. burst 参考答案:B 答案解析:根据题意,应该是分析声波的曲线图,实际是通过电子仪器把声音转换成曲线的形式表现出来。因此正确答案是B。其他选项都不符合题意。