whAt's thE mAin point thE spEAkEr mAkEs
A．ContEnt oF spEECh is morE importAnt thAn tonE oF voiCEs.
B．voiCE quAlity hAs A strong EFFECt on listEnErs.
C．EFFECtivE spEAkErs must usE visuAl AiDs.
D．AmpliFying DEviCEs ArE EssEntiAl in lArgE rooms.