如同前面指出的那样，在内容模型中应该使用元素实体而不是文字元素名称。

As noted previously, you should use element entities instead of literal element names in content models.

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观赏者必须感觉到它是一个单一的实体形态，而完全不靠它的食用意义或它会变成鸟这样的文字概念来感觉。

He must, for example, perceive an egg as a simple single solid shape, quite apart from its significance as food, or from the literary idea that it will become a bird.

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字符和已解析实体引用替换为文字字符(特殊字符除外)。

Character and parsed entity references are replaced with the literal characters (excepting special characters).

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