1) Sound is the kind of  a) work b) energy c) force d) none 2) vibration is a) visible b) invisible  c) can both (a) and (b)  d) non 3) sound can not be produce without vibrations a) true b) false

Leaderboard

Estilo ng visual

Mga pagpipilian

Magpalit ng template

Ibalik ng awtomatikong pag-save: ?