问答题 Practice 2　　On some occasions it is important to adhere to the conventions that characterize serious public discourse and to avoid expressions that we might use in more casual situations. Among the features of formal English are the careful explanation of background information, complexity in sentence structure, explicit transitions between thoughts, and the use of certain words that are reserved chiefly for creating a formal tone. Situations that normally require formal usage would include an article discussing a serious matter submitted to a respected journal, an official report by a group of researchers to a government body, a talk presented to a professional organization, and a letter of job application.

问答题 Practice 1　　Biological diversity, or biodiversity, means the variety of life on earth and includes the entire web of living organisms ranging from soil microbes, frogs, and trees to bears and blue whales. From the perspective of sustainable use, wildlife is a renewable resource that provides many benefits and socioeconomic advantages. Sustainable use is defined as “the use of components of biodiversity in a way and at a rate that does not lead to long term decline” but maintains the “potential to meet the needs and aspirations of present and future generations.”

问答题 Practice 4　　In the first year or so of Web business, most of the action has revolved around efforts to tap the consumer market. More recently, as the Web proved to be more than a fashion, companies have started to buy and sell products and services with one another. Such business-to-business sales make sense because businesspeople typically know what product they’re looking for.　　Nonetheless, many companies still hesitate to use the Web because of doubts about its reliability. “Businesses need to feel they can trust the pathway between them and the supplier,” says senior analyst Blane Erwin of Forrester Research.

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