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某企业A材料年需要量为48000公斤，年单位储存成本8元，单位缺货成本12元，每次进货费用50元。 [要求] 计算A材料的经济进货批量和平均缺货量。
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上下楼梯，一般应靠而行；为人引路时，应走在（）位置，并伸出右手作引导状。
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葡萄酒酿造发酵一般需要多长时间？（）
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Books are not Nadia Konyks thing. Her mother, hoping to attract her, brings them home from the library, but Nadia rarely shows an interest. Instead, like so many other teenagers, Nadia, 15 , is addicted to the internet. She regularly spends at least six hours a day in front of the computer. Nadia checks her e-mail and reads carefully through myyearbook. com, a social networking site, reading messages or posting updates on her mood. She searches for music videos on youtube. com and logs onto gaiaonline. com, a role-playing site where members exchange identities as cartoon characters. But she spends most of her time on quizilla. com or fan fiction. net, reading and commenting on stories written by other users and based on books, television shows or movies. Her mother, Deborah Konyk, would prefer that Nadia read books for a change. But at this point, Ms. Konyk said, "Im just pleased that she reads something anyway. " Children like Nadia lie at the heart of a passionate(狂热的)debate about just what it means to read in the digital age. As teenagers scores on standardized reading tests have declined, some argue that the hours spent surfing the Internet is the enemy of reading—reducing literacy, destroying attention spans and a valuable common culture that exists only through the reading of books. But others say the Internet has created a new kind of reading, one that schools and society should not discount. The web inspires a teenager like Nadia, who might otherwise spend most of his leisure time watching television, to read and write. Even talented book readers like Zachary Sims, 18, of old Greenwich, Conn. , crave the ability to quickly find different points of view on a subject and talk with others online. Some children with dyslexia(诵读困难)or other learning difficulties, like Hunter Gaudet, 16, of Somers, Conn. , have found it far more comfortable to search and read online.The underlined sentence in Paragraph 1 means______.A．Nadia prefers not to be a writerB．Nadia doesn"t like to buy booksC．Nadia treats reading books as a piece of cakeD．Nadia shows no interest in reading books
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在熨躺柞丝绸面料时，必须（）。
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对竞争对手信息分析的目的是为了确保本餐厅的（）。
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装配尺寸链中的（）存在于零部件之间，而绝对不在零件上。
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临界水分是在一定空气状态下，湿物料可能达到的最大干燥限度。
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在个别资本成本的计算中，不必考虑筹资费用影响因素的是()。
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根据险种的不同,再保险可以分为( )和( )。