4. • By planting nearly 20 million trees, the earth, and its population will be provided
with 260 million more tons of oxygen.Those same 20 million trees will also
remove the 10 million tons of CO2.
5. • The limbs of a tree are not perfectly round.They have a compression side (the
upper side) and a tension side (lower side) which enables them to support their
own weight plus the weight of the leaves, nuts, or fruits, suspended in mid-air.