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2014年职称英语理工类教材学习部分内容及解析 Rhythm controls everything in Nature. ___1___. The sun provides a basic time rhythm for all living creatures including humans. Nearly all animals are influenced by sun cycles and have developed a biological clock in their bodies following these cycles. The moon also exerts its force and influence on the sea. Its gravitational attraction causes the rising of the tide. ___2___. When the moon is behind the Earth, centrifugal force causes the second tide of the day. Animals living in tidal areas must have the instinct of predicting these changes, to avoid being stranded and dying of dehydration. Since the time of the dinosaurs, the king crab has been laying eggs1 at the seaside in a set way2. To avoid predator fish3, the eggs are always far from seawater and protected by sand. In the following two months, the eggs undergo dramatic changes related to the cycles of the moon4. When the second spring tide comes, the young king crabs have matured. ___3___. . Most of the mammals, either the giant elephant or the small shrew, have the same average total number of heartbeat in their lifetime. Shrews live only for two and a half years, and spend their life at a high speed and high tempo. Animals like shrews with a pulse rate of 600 per minute have an average total of eight hundred million heartbeats5 throughout their life. The African elephant has a pulse rate of 25 beats per minute, and a life span6 of 60 years. The size of the body determines the speed of life. ___4___. | 
