这种模型还可以用于在提供者和使用者之间创建紧密的反馈环节；例如 eBay（有关其链接，请参见 参考资料）上买家和卖家的等级系统。
This model is also being used to create a tight feedback loop between providers and consumers; an example of this is the buyer and seller rating systems on eBay (see Resources for a link).
今天，组织结构体现为超链接，而不是等级制。
免费的目录通常要求交换链接，但是你应该记住，如果你有在你的网页有很多链接，搜索引擎可以减少您的网页搜索引擎结果排名或等级。
The free directories usually ask for link exchange, however you should remember that if you have many links on your web page, search engines can reduce your page ranks or rank on search engine result.
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