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简述环境标准的分类、分级及使用原则。
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计算机信息系统的安全保护
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Scientists were embroiled (使卷入) last week in an international row over genetically modified cotton (GM cotton).A study in China suggested for the first time that the crop was permanently damaging the environment and that insects were building up resistance to it.The study, by the Nanjing institute of Environmental Science, combined the laboratory and field work from four Chinese scientific institutes. The study was done over a several - year period.GM Cotton had a gene resistance to the cotton bollworm (棉铃虫) and isolated from the bacterium (细菌) named Bacillus thuringiensis (Bt), but the study found that it harms the natural parasitic (寄生的) enemies of the cotton bollworm.It also indicated that populations of pests besides the bollworm had increased in Bt cotton fields and some had replaced the bollworm as the primary pest.However, the leading GM company, the US's Monsanto, which controls more than 80 per cent of the Bt cotton grown worldwide, dismissed the research.It said that the industry has always cited GM cotton as its biggest success, because it can increase yields by up to 60 per cent and reduce the need for pesticides (杀虫剂) by 80 per cent.But, unfortunately for the industry, (80) the scientists also found that the resistance of Bt cotton to bollworm decreased significantly over time.Why scientists say no to GM cotton?A．Because the cotton was genetically modified.B．Because the cotton was found to damage the environment.C．Because the cotton harms the bollworm.D．Because Monsanto dismissed the research.
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关于儿童生长颅骨骨折，下列哪项不正确（）。
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管内穿放大对数电缆或4芯以上光缆时，弯管路的管径利用率应为（）。
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患者，女性，20岁。心慌、多汗，胃纳亢进伴消瘦2个月余就诊。体检：甲状腺Ⅱ度肿大，右上极可闻及血管杂音患者被诊断为"Graves病"，下列哪项是最不可能出现的（）
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垂直于屋脊铺贴时，卷材应搭接于屋脊下面至少（）以下。
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线粒体基因组有什么特点？
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下列各项中，属于资产要素特点的有（ ）。
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《素问•灵兰秘典论》指出“小肠者，受盛之官，化物出焉。”的“化物”应该解释为（）