...Communications Company, Inc. If humans continue to use fossil fuels in a business as usual manner for the next few centuries, the polar ice caps will be depleted, ocean sea levels will rise by seven meters and median air temperatures will soar to 14.5 degrees warmer than current day. These are the stunning results of climate and carbon cycle model simulations conducted by scientists at Lawrence Livermore National Laboratory. By using a coupled climate and carbon cycle model to look at global climate and carbon cycle changes, the scientists found that the earth would warm by 8 degrees Celsius (14.5 degrees Fahrenheit) if humans use the entire planet's available fossil fuels by the year 2300. The jump in temperature would have alarming consequences for the polar ice caps and the ocean, said lead author Govindasamy Bala of the Laboratory's Energy and Environment Directorate. In the polar regions alone, the temperature would spike more than 20 degrees Celsius, forcing the land in the region to change from ice and tundra to boreal forests. "The temperature estimate is actually conservative because the model didn't take into consideration changing land use such as deforestation and build-out of cities into outlying wilderness areas," Bala said. Today's level of atmospheric carbon dioxide is 380 parts per million (ppm). By the year 2300, the model predicts that amount would nearly quadruple to 1,423 ppm. In the simulations, soil and living biomass are net carbon sinks, which would extract a...
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...How is the scientific method used to solve problems? Scientific method used to solve problems by keen observations, rational analysis, and experimentation. Observation: Closely observe the physical world around you. How is the scientific method used to solve problems? Scientific method used to solve problems by keen observations, rational analysis, and experimentation. Observation: Closely observe the physical world around you. Question: Recognize a question or a problem. Hypothesis: An educated guess or a reasonable explanation. When the hypothesis can be tested by experiment, it qualifies as a scientific hypothesis Prediction: Consequences that can be observed if the hypothesis is correct. The consequences should be absent if the hypothesis is not correct. Conclusion: Formulate the simplest general rule that organizes the hypothesis, predicted effects, and experimental findings. What is the principle of falsifiability? For a hypothesis to be considered scientific it must be testable?it must, in principle, be capable of being proven wrong. Fact: A phenomenon about which competent observers can agree. Theory: A synthesis of a large body of information that encompasses well-tested hypotheses about certain aspects of the natural world. Law: A general hypothesis or statement about the relationship of natural quantities that has been tested over and over again and has not been contradicted. Also known as a principle. Evidence: which...
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...CONTENT Exercise 1. 2 Exercise 2. 5 Exercise 3. 8 Exercise 4. 11 Exercise 5. 15 Exercise 6. 18 Exercise 7. 21 Exercise 8. 25 Exercise 9. 28 Exercise 10. 31 Exercise 11. 34 Exercise 12. 37 Exercise 13. 40 Exercise 14. 43 Exercise 15. 46 Exercise 16. 49 Exercise 17. 53 Exercise 18. 57 Exercise 19. 61 Exercise 20. 65 Exercise 21. 68 Exercise 22. 72 Exercise 23. 76 Exercise 24. 80 说明： 题目来源： Exercise 1-24：所有题目都来自官方真题 其中： Exercise 1-14：我们将OG和PP2中的题目编排为前14个Exercise, 每个Exercise都是按照GRE考试中阅读部分的出题习惯编排，即每个Exercise 10个题目，形式为（1长+2短+1逻辑 or 4短+1逻辑）。 Exercise 15-24：我们将近年来考试中出现的文章和老GRE中极为接近现行出题风格的文章编排为后10个Exercise，每个Exercise 13个题目左右，形式为（1长+1短+2逻辑）。 练习方法： 建议大家第一遍做能够限时练习，按照考试的要求每个Exercise的大致难度和应该用的时间都标在了前面。没做完6个exercise可以做一个回顾总结，将文章反复做一遍，总结单词，长难句，文章的出题规律，句子之间的关系。 答案显示方法： 如果你打印出来练习：参考答案见P 页 如果你在电脑上练习：windows 系统：Ctrl+Shift+8；Mac系统：Command+8 Exercise 1. 20min While most scholarship on women’s employment in the United States recognizes that the Second World War (1939–1945) dramatically changed the role of women in the workforce, these studies also acknowledge that few women remained in manufacturing jobs once men returned from the war. But in agriculture, unlike other industries where women were viewed as temporary workers, women’s employment did not end with the war. Instead, the expansion of agriculture and a steady decrease in the number of male farmworkers combined to cause the industry to hire more women in the postwar years...
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