声波的传播需要媒介，这种媒介可以是空气、水、玻璃或金属。
Sound waves need a medium through which to travel, whether it's air, water, glass or metal.
给(玻璃或金属)加热并使之慢慢冷却以使之变硬并减少易碎性。
To subject (glass or metal) to a process of heating and slow cooling in order to toughen and reduce brittleness.
如果使用得当，该产品将不会损伤塑料，橡胶，涂料，纺织，玻璃或金属。
If used properly, the product will not attack plastics, rubber, paint, textiles, glass or metal.
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