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                ## HTML5 為什么只需要寫 `<!DOCTYPE HTML>`,而不需要引入 DTD? HTML5 不基于 SGML,因此不需要對 DTD 進行引用,但是需要 DOCTYPE來規范瀏覽器的行為(讓瀏覽器按照它們應該的方式來運行)。 而 HTML4.01 基于 SGML ,所以需要對 DTD 進行引用,才能告知瀏覽器文檔所使用的文檔類型。
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                              哎呀哎呀视频在线观看