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在研究“空气是传播声音的重要物质”的实验时,教科书通常是这样要求的:把玻璃罩里的空气抽掉,里面成了真空,我们就只能看见闹钟的铃在动,却听不见声音(如图1所示)。
In the study of “The Air is an Important Material for Propagating Sounds,” textbooks usually require that the air in the glass be removed and the inside becomes a vacuum, and we can only see the bell of the alarm moving Can not hear the sound (as shown in Figure 1).