The reason for this is easy to recognise: in nature, the existent organisms either adapt or are regularly replaced by new types.
原因很容易理解：在自然界中，现存的生物要么适应环境，要么被新物种取代。
Hospital beds were scarce and medicines were practically non-existent.
当时医院病床紧缺，药物根本所剩无几。
Though no fault of their own, they can suddenly find their productivity deteriorating or quality control non-existent.
虽然不是他们自己的错，但他们会突然发现自己的生产率下降或质量管理失控。
"The evidence for kitelifting is non-existent," says Willeke Wendrich, an associate professor of Egyptology at the University of California, Los Angeles.
加州大学洛杉矶分校埃及学副教授韦利克·文德里希说：“没有证据证实（古埃及人利用）风筝抬起重物。”
The Chinese doctor took my pulse and asked to see my tongue, both of which were new experiences to me because they are both non-existent in Western medicine.
中医给我把脉并要求看我的舌头，这对我来说都是全新的经历，因为在西医中，这些都是不会有的。
Traceability among information elements is either limited or non-existent.
信息要素之间的可追溯性是受限的，或不存在的。
Much x86 hardware has poor, limited, or non-existent support for ECC memory.
许多x86硬件只对ECC内存提供可怜的、有限的支持，甚至不提供支持。
However, you can access potentially non-existent entries safely, using the get function.
不过，您可以使用get函数，安全地访问一个可能不存在的条目。
Current pension systems are all too often unsustainable, partial, fragmented or non-existent.
当前的养老金体制通常不具有可持续性、片面、支离破碎或根本不存在。
In areas where health systems are weak or virtually non-existent, basic data will not be collected.
在卫生系统薄弱或事实上不存在的地区，是不会收集基本数据的。
When times are good, volumes are usually high; but when times are bad, they can be non-existent.
在光景好的时候，交易量总是保持高位；但在光景不好时，甚至可能出现无交易量的情形。
Piracy is not that uncommon in societies where the national state is either weak or non-existent.
在民族国家不是弱小就是难以存活的社会中，海盗并不罕见。
Another problem is that people can leave money to non-existent charities; "cancer relief" being a common example.
另外一个问题是，立遗嘱的人可能会将遗产馈赠给不存在的慈善机构；“抗癌机构”就是一个经常碰到的例子。
It has always been more about creating demand for real estate in places where water was scarce or non-existent.
而是为那些水资源匮乏或根本没水地区的房地产创造了需求。
External forces like the hostile FDA or non-existent IPO markets are conspiring against certain VC-backed companies.
严苛的美国食品药品管理局(FDA)和消失的IPO市场等外部力量让某些依赖风投支持的公司处于不利境地。
A "delete" operation that tries to remove the non-existent home phone would succeed but have no effect on the document.
尝试删除不存在的家庭电话号码的“delete”操作会成功，但是对文档没有影响。
His business is stagnant, he has the roommate from hell, and since his divorce, his love life is completely non-existent.
他的生意状况很不好，同屋的室友令人无法忍受，自从他离婚后爱情生活又是一片空白。
That is why the book discusses ways to provide alternative co-existent behaviors and explains how to bridge them, when necessary.
这也是为什么本书讨论了提供两种模式并存的方式，也解释了必要时如何在两者之间取得平衡。
I was really fascinated by the appearance of a non-existent place that the Internet had the power to make real and give a semi-existence.
一个本不存在的地方，但互联网有能力使它变得真的一样，让它半真半假地存在。这一切都让我很着迷。
Mainstream media coverage is generally restricted to the society columns, and the game's television presence is virtually non-existent.
大众媒体对其报道大多局限于社会新闻版，马球比赛上电视的机会几乎不存在。
Open Axis will work to define a standard integration schema using XML, which will bring valuable enhancements to existent XML standards.
OpenAxis将通过XML来定义其标准整合架构，这将给现有的XML标准带来重大的改进。
If it were only for the sake of an idea Copernicus would have smashed the existent macrocosm and Columbus would have foundered in the Sargasso Sea.
如果仅仅是为了一个观念，哥白尼本会砸烂整个现存宇宙的，哥伦布也会葬身马尾藻海。
In the past 30 years, the flow of people between the United States and China has gone from virtually non-existent to the hundreds of thousands.
在过去的30年里，美中两国间的人员流动从几乎没有到数十万。
Controls that reference non-existent instance elements will either fail to render, or generate an error message (depending on your XForms implementation).
引用不存在的实例元素的控件要么不能呈现，要么生成错误消息(取决于XForms实现)。
The rush to protect a possibly non-existent bird's habitat may seem odd: but, if discovered, the creature would be protected by the Endangered Species Act.
这一保护一种可能不存在的鸟类的栖息地的热潮看起来也许很奇怪，但是一旦发现，这一物种将受到频危物种法案的保护。
The rush to protect a possibly non-existent bird’s habitat may seem odd: but, if discovered, the creature would be protected by the Endangered Species Act.
这一保护一种可能不存在的鸟类的栖息地的热潮看起来也许很奇怪，但是一旦发现，这一物种将受到频危物种法案的保护。
Matters are even worse in the desert West and lowland South, where population growth has been so rapid that basic infrastructure is often non-existent.
西部沙漠区和南部低地区的情况更糟，那里人口增长过快，往往看不见什么基础设施。
Matters are even worse in the desert West and lowland South, where population growth has been so rapid that basic infrastructure is often non-existent.
西部沙漠区和南部低地区的情况更糟，那里人口增长过快，往往看不见什么基础设施。
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