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> 一列连续鸣笛的火车高速从铁道上通过，则在铁道边上的人听到的笛声应为 A．某一不变频率的笛声 B．车头经过前听到的笛声比声源频率高，车头经过后听到的笛声比声源频率低 C．车头经过前听到的笛声比声源频率低，车头经过后听到的笛声比声源频率高 D．频率时高时低周期性变化的笛声

问题：

发布时间：2024-09-13

一列连续鸣笛的火车高速从铁道上通过，则在铁道边上的人听到的笛声应为

A．某一不变频率的笛声

B．车头经过前听到的笛声比声源频率高，车头经过后听到的笛声比声源频率低

C．车头经过前听到的笛声比声源频率低，车头经过后听到的笛声比声源频率高

D．频率时高时低周期性变化的笛声

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