[单项选择]Trees are so common arid quiet that we pay them little mind. What, for instance, should we answer when asked to name the biggest living thing Earth has ever seen Dinosaurs Blue whales No, the largest sequoias in northern California weigh more than six blue whales. The tallest redwoods and Australian eucalyptus trees tower more than 300 feet high, three times the length of the greatest dinosaur.
(71) Some bristlecone pine trees in the American West are more than 4, 000 years old, seedlings at the time the Egyptians were building the Pyramids.
Trees sustain our lives and our planet in a thousand practical ways. This morning at breakfast—in your wood-framed house, on your wooden kitchen table—you might have enjoyed orange juice or a grapefruit. Both come to use from trees. Over your French toast you may have sprinkled cinnamon and nutmeg, the powdered bark and nuts of tropical trees. That quart of maple syrup on your table was boiled down from roughly 10 gallons of sap f
A. For centuries, the Chinese have derived medicines from the ginkgo tree.
B. Through photosynthesis, an acre of trees produces enough oxygen to sustain three humans.
C. As scientists unlock the secrets of trees, they uncover surprising tacts.
D. Trees have always been green machines, producing substances that humans learned to use.
E. You think, at 150 or more years, giant tortoises can live a long time
F. And the morning newspaper was printed on the processed wood pulp we call paper.