documentclass[11pt]{article}

begin{document}

   This is another

   begin{comment}

       rather stupid,

       but helpful

   end{comment}

   example for embedding

   comments in your document.

end{document}

上述例子编译后出现上述错误，可改为：

documentclass[11pt]{article}

newcommand{comments}[1]{}

begin{document}

   This is another

   comments{

   rather stupid,

   but helpful

   }

   example for embedding

   comments in your document.

end{document}