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Sound
For humans, hearing is limited to frequencies between about 20 and 20,000 Hz, with the upper limit generally decreasing with age.
Sound is transmitted through gases, plasma, and liquids .The speed of sound depends on the medium through which the waves are passing.
Equipment for generating or using sound includes musical instruments, hearing aids and sonar systems.
والثاااني عن الشمووع
Candles
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Until about 150 years ago, candles provided the only from of lighting in people's houses.
A Candles was made of animals fat with a string running through it.
When the string was lit, the candles burned and gave off a dim light.
As for me I like candles a lot. They look very romantic.
I like their different colors and shapes.
Candles nowadays are perfumed so whenever you lit a candle a nice smell will spread filling the place.