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We think that the duty of the police is to (sure)（）that people are protected from crime.
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Solar energy is called a renewable resource because on a human time scale it is essentially inexhaustible, it is expected to last at least 6.5 billion years while the sun completes its life cycle. 46) A potentially renewable resource can be renewed fairly rapidly (hours to several decades) through natural processes, examples of which include forest trees, grassland grasses, wild animals, fresh lake and stream water, groundwater, fresh air, and fertile soil. 47) One important potentially renewable resource for us and other species is biological diversity or biodiversity, which consists of the life forms that can best survive variety of conditions currently found on Earth. Kinds of biodiversity include (1) genetic diversity( variety in the genetic makeup among individuals within a single species), (2) species diversity (variety among the species or unique forms of life found in different habitats of the planet), and ( 3 ) ecological diversity (variety of forests, deserts, grasslands, streams, lakes, oceans, wetlands, and other biological communities). 48)This rich variety of genes, species, and biological communities gives us food, wood, fibers, energy, raw materials, industrial chemicals, and medicines―all of which pour hundreds of billions of dollars into the world economy each year. Earth’’s vast list ’’of life forms and biological communities also provides free recycling and purification services and natural pest control. Potentially renewable resources, however, can be exhausted. 49)The highest rate at which a potentially renewable resource can be used indefinitely without reducing its available supply is called its sustainable yield. If a resource’’s natural replacement rate is exceeded, the available supply begins to shrink―a process known as environmental degradation. Several types of environmental degradation can change potentially renewable resources into nonrenewable or unusable resources. In the United States, one-fourth of the groundwater withdrawn each year is not replenished (filled up again). Between 25% and 50% of the world’’s wetlands (55% in the U. S. ) have been drained, built upon, or seriously polluted. Almost half of the world’’s tropical forests have been cleared. Thousands of wildlife species become extinct each year, mostly because of human activities. If habitat destruction continues at present rates, as many as 1.5 million species could disappear over the next 25 years―a drastic loss in vital Earth capital. 50)These examples help explain why most environmental scientists believe that over the next few decades, the danger of degradation and exhaustion is greatest for potentially renewable resources, not nonrenewable resources ( except for petroleum and perhaps a few scarce minerals for which we can’’t find economically and environmentally acceptable substitutes). Solar energy is called a renewable resource because on a human time scale it is essentially inexhaustible, it is expected to last at least 6.5 billion years while the sun completes its life cycle. 46) A potentially renewable resource can be renewed fairly rapidly (hours to several decades) through natural processes, examples of which include forest trees, grassland grasses, wild animals, fresh lake and stream water, groundwater, fresh air, and fertile soil. 47) One important potentially renewable resource for us and other species is biological diversity or biodiversity, which consists of the life forms that can best survive variety of conditions currently found on Earth. Kinds of biodiversity include (1) genetic diversity( variety in the genetic makeup among individuals within a single species), (2) species diversity (variety among the species or unique forms of life found in different habitats of the planet), and ( 3 ) ecological diversity (variety of forests, deserts, grasslands, streams, lakes, oceans, wetlands, and other biological communities). 48)This rich variety of genes, species, and biological communities gives us food, wood, fibers, energy, raw materials, industrial chemicals, and medicines―all of which pour hundreds of billions of dollars into the world economy each year. Earth’’s vast list ’’of life forms and biological communities also provides free recycling and purification services and natural pest control. Potentially renewable resources, however, can be exhausted. 49)The highest rate at which a potentially renewable resource can be used indefinitely without reducing its available supply is called its sustainable yield. If a resource’’s natural replacement rate is exceeded, the available supply begins to shrink―a process known as environmental degradation. Several types of environmental degradation can change potentially renewable resources into nonrenewable or unusable resources. In the United States, one-fourth of the groundwater withdrawn each year is not replenished (filled up again). Between 25% and 50% of the world’’s wetlands (55% in the U. S. ) have been drained, built upon, or seriously polluted. Almost half of the world’’s tropical forests have been cleared. Thousands of wildlife species become extinct each year, mostly because of human activities. If habitat destruction continues at present rates, as many as 1.5 million species could disappear over the next 25 years―a drastic loss in vital Earth capital. 50)These examples help explain why most environmental scientists believe that over the next few decades, the danger of degradation and exhaustion is greatest for potentially renewable resources, not nonrenewable resources ( except for petroleum and perhaps a few scarce minerals for which we can’’t find economically and environmentally acceptable substitutes).
How to Write an AbstractThe rules for writing an abstract (摘要) are almost the same to those for writing the summary of an investigation report. In an abstract you make an outline of the problem and the purpose of your investigation, mention very briefly how you conducted the investigation or tests, describe your main findings, and make the conclusions. All these must be done in as few words as possible: ideally, your abstract will be about 125 words long and never more than 250 words.From the abstract, readers must be able to decide whether the information you provide in the scientific paper or report is particularly interesting to them and whether they should read further. Because a scientific paper is written for readers who generally are familiar with your technical or scientific discipline (学科), you may use technical terminology (术语) in the abstract. The abstract should be written last, when the Whole paper has been written, so that you can make an abstract of the brief details you need from what you have already written. Why can you use technical terminology in the abstract Because our readers are usually（）our scientific discipline.
I’ve got my performance (appraise)（）this month with my manager.
Psychology is the study of the mind and mental activities. For example, psychologists are interested in why some things make you sad, but others make you happy. They want to know why some people are shy, but others are quite talkative. They also want to know why people do the things that they do. They test intelligence.Psychologists deal with the minds and behavior of people. Your mind consists of all your feelings, thoughts, and ideas. It is the result of one part of the brain called the cerebrum (大脑). Your behavior is the way you act or conduct yourself. Examples of behavior include shouting, crying, laughing and sleeping.Several people have been instrumental in the field of psychology. Wilhelm Wundt set up the first psychological laboratory in Leipzig, Germany, in 1879. Ivan Pavlov, a Russian, is noted for his experiments with dogs in which he studied their reflexes (反射作用) and reactions. Around 1900, Sigmund Freud stated his theory that people try to repress any memo- ties or thoughts that they believed were not good.Psychologists should not be confused with psychiatrists. Psychiatrists deal only with mental illness. They are medical doctors who treat people. The cerebrum controls（）
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