thE mAin iDEA oF this pAssAgE is ______.
A．pArEnts shoulDn't smokE
B．ChilDrEn shoulD AvoiD smoking
C．thE AFFECts oF smoking AnD sEConD-hAnD smokE is hArmFul
D．my mothEr AnD grAnDpArEnts smokED hEAvily