(1)控制噪声的方式有三种:防止噪声产生,阻断噪声传播和防止噪声进入耳朵。车门车窗己关闭的汽车内的乘客几乎听不到外面的声音,这是从 的 方式减少噪声;广州市区内禁鸣喇叭是从____的方式减少噪声。 (2)下表列出了声音在一些介质中传播的速度: 认真阅读上表,你一定能有所发现,请任意写出两条: a. ; b. 。
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【单选题】When I took his temperature, it was three degrees above ______.
【简答题】democracy imagination different flexibility overcome online offer traditional modern regular make possess place perform big Learning shouldn't be limited to a campus or a classroom anyone. If you have...