When you watch TV programs about wild animals, it is surprising to see how an antelope (羚羊) can run away from a strong lion. In the wilderness, everyone has his own way to protect himself. Even plants have their own ways to fight off enemies.
Over millions of years, plants have developed their own defense system (防卫系统). Chemicals(化学物) are fantastically used by plants to survive . By making their leaves, flowers, roots and fruits poisonous (有毒的) to enemies, plants can fight back.
One such plant is the Golden Wattle tree. The British scientist David Cameron has found when an animal eats the tree's leaves, the amount (数量) of poison increases in the other leaves. "It's like the injured leaves telephoning the others to fight together against the enemy", he said.
The tree also sends defense messages to neighboring plants by giving out a special smell. Golden Wattle trees in the nearby 45 meters will get the message and produce more poison within 10 minutes. Now, if an enemy eats too many of the trees' leaves, he will die.
Every kind of plant or tree is good at producing a special set of chemicals. Herbivores, like rabbits, can safely eat the leaves of one tree, but they may be poisoned by its neighbor.
In this way, plants have not only developed their own defense system, but also shared it with others. This makes it impossible for a single animal to destroy even a small area of forest.
From the first 2 paragraphs, we can learn that_______.

A．plants can do nothing against their enemies

B．chemicals are quite useful for plants to survive

C．an antelope can always run away from a strong lion

D．leaves, roots, flowers and fruits of plants are poisonous

The underlined word "herbivores" in the 5th paragraph probably means animals which_______.

A．produce poison	B．live on small animals
C．like to eat rabbits	D．feed on plants or grass

The last paragraph of the passage suggests that this kind of defense system is_______.

A．bad for animals	B．good for forests
C．helpful to some animals	D．harmful to forests

The passage is mainly about_____________________.

A．the examples of protecting forests

B．the balance between animals and plants

C．the ways of plants fighting against enemies

D．the relationship between lions and antelopes