单项选择题

以下关于EDI的说法中，错误的是：

A.EDI文件数据一般通过增值网或专用网来传输数据
B.EDI采用的标准和格式不是固化的，可以不统一
C.使用EDI可以提高工作效率，降低成本，节省库存费用，减少数据的错误
D.在传输文件前，对转换成EDI格式的文件需要在外层加上通信交换信封

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'Hidden' Species May Be Surprisingly CommonCryptic(隐蔽的；隐藏的)species -- animals that appear identical but are genetically quite distant --may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity(生物多样性)estimates and wildlife management, to our understanding of infectious diseases and evolution.Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA (脱氧核糖核酸) sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat in Frankfurt, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographical(生物地理学的)regions.Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles(爬行动物), and were more likely to occur in tropical rather than temperate(温带的)regions. 'Species that are seemingly widespread and abundant could in reality be many different Cryptic species that have low populations and are highly endangered,' says Pfenninger. Until the genetic information of all species in at least one taxon(分类单元)is thoroughly studied, no one will know just how many cryptic species exist, 'It could be as high as 30%,' Pfenninger says.'I'm extremely surprised by their results, ' says Alex Smith of the University of Guelph in Ontario, CanadA.'It's a call to arms to keep doing the broad kind of genetic studies that we are doing. 'Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will be able to decide how many cryptic species exist throughout the animal kingdom.Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding (非杂交繁殖的) species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU).The reclassifications are more than an academic exercisE.They define populations that have evolved independently of each other and whose genetic differences can have significant consequences.In the early 1900s misidentification of mosquito species based on morphology confused: attempts to control malaria(疟疾)in EuropE.Ultimately, what was thought to be a single species was actually made up of six sibling(同胞，同属)species, only three of which transmitted the diseasE.' The basic unit in biology is always the species, and you have to know what you are dealing with,' Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studieD.Which of the following about the significance of the research on cryptic species is NOT true?A.The results of the research can help the development of many other research areas.B.The results of the research can help the development of biodiversity estimates.C.The results of the research can help our understanding of infectious disease evolution.D.The results of the research can help our understanding of 'survival of the fittest'.

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单项选择题

根据企业生命周期理论，企业最关心如何获得足够的资金问题的期间是：

A.投入期到成长期
B.成长期到成熟期
C.成熟期到衰退期
D.衰退期到初创期