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American scientist say that they believe trees can warn each other of danger releasing chemicals into the air.__1__ The theory was announced by the National Science__2__ Foundation is the result of studies carried out by scientist in the states of Washington and New Hampshire. The scientists said they found that when trees are against attack by disease or insects, nearby__3__ trees take the same offensive actions as the trees__4__ being attacked. And they said it appears that the trees being attacked may produce and send out chemicals to warn the other trees. A United Nations'report says Asian countries are faced major environ-__5__ mental problems. The report released in Bangkok said that parts of China, India, Iran, Afghanistan and Pakistan were threatened by man-made and natural__6__ events that turn productive land into deserts. I said the most serious threat against the area is the rapid expansion of Asia's rain forests, or woods, especially__7__ in Malaysia, the Philippine and Thailand. The report said the reduction in woods areas have already led to __8__ increased flooding, water shortages in the dry seasons and the loss of farm lands. A top UN official said that as much as 70% of the woods in Asia would be gone in__9__ 20 years unless actions are taken now to save it.__10__
