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根据我国《海船船员发证规则》规定,值班水手、值班机工适任证书等级分为______。
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根据我国《海船船员发证规则》规定,电子电气员和电子技工适任证书适用于____。
Water is life. We depend on it to keep us and the (1) ____healthy. Nonetheless, many people take water as a natural resource for granted. Today, the situation has changed. As the population of the world increases, and with it the demand for water, there is growing concern that our water supplies will not be as (2) ____ as we think. Eighty countries now have water shortages and 2 billion people lack access to clean water. One billion people lack enough water to simply meet their basic needs.While nearly 70 percent of the world is covered by water, only 2.5 percent of it is fresh. This tiny amount of fresh water available on the planet has remained fairly constant over time and is (3) ____unevenly around the world. The growth of the world population, therefore, (4) ____ competition for a clean supply of water every year. Worse still, humans are not efficient users. According to the United Nations, water use has grown at more than twice the (5) ____ of population increase in the last century. The reality is that an increasing number of regions are (6) ____ with water scarcity. By 2025, two-thirds of the world’s population may face water shortages.An adequate and (7) ____ water supply is essential to the future of every country. To increase and conserve supplies of fresh water, many countries have been working at technological (8) ____, one of which is in the process of desalination. New filtration systems have been developed to (9) ____ traditional heating methods. Thus the expected (10) ____ can be achieved: lower costs.A.abundant B. complicated C. conflict D. confrontedE. distributed F. environmentG. highlightH. innovations I. intensified J. outcomeK. rateL. reliableM. replace N. sourcesO. Subsequent
人类社会经历了五次信息技术的革命。
信息技术的不断发展，会给人们的日常学习、工作和生活带来全面而深刻的影响
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