A、By storing large quantities of carbon dioxide.B、By developing ways to protect themselves.C、By producing a large amount of oxygen.
（2）、Why do the leaves of a tree never actually touch those of others?
A、Because it's a way to prevent the spread of tree diseases.B、Because it makes it difficult for insects to eat leaves.C、Because animals can jump between them.
（3）、How much rain rainforests produce sometimes in a year?
A、About 75% of their own rain.B、As much as 430 inches.C、About 10-20 feet.
