The world is f_ with many interesting sounds.We make sounds by making things m_ to

The world is f_ with many interesting sounds.We make sounds by making things m_ to
is called vibration.It means moving up and down or forwards and backwards very fast.These vibrations cause the air to vibrate.This makes sound waves.And there are different k_ of sounds.Some sounds are soft,some sounds are loud.Soft sounds are made by w_ vibrations,loud sounds are made by strong vibrations.Low sounds are made by slow vibrations and h_ sounds are made by fast vibrations.首字母填空