A．By watching some films about World Environment Day.B．By listening to some lectures and planting trees, etc.C．By planting trees, having some green concerts, bicycle parades, etc.D．By delivering some speeches about World Environment Day.
A．By watching some films about World Environment Day.
B．By listening to some lectures and planting trees, etc.
C．By planting trees, having some green concerts, bicycle parades, etc.
D．By delivering some speeches about World Environment Day.