我提交了以下网站进行验证，并收到此错误：
错误：
No DOCTYPE found! Checking with default XHTML 1.0 Transitional Document Type.
No DOCTYPE Declaration could be found or recognized in this document. This generally means that the document is not declaring its Document Type at the top. It can also mean that the DOCTYPE declaration contains a spelling error, or that it is not using the correct syntax.
The document was checked using a default "fallback" Document Type Definition that closely resembles “XHTML 1.0 Transitional”.
我尝试将DOC类型更改为：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
然而它仍然会发现错误？
非常感谢任何建议，谢谢
答案 0 :(得分：2)
我无法在源代码的顶部看到doc类型。我添加了一个并通过W3 checker手动验证了代码，并且在没有警告的情况下通过了与文档类型相关的内容。
这是我添加的文档类型
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">