Why cannot I replace the regular expression in php?

Why cannot I replace PHPcode & lt; with php regular expressions ;? Php $ page = '& lt ;! -- WebAppleHeader -- & gt; & lt; divclass = & quot; sheader & quot; & gt; & lt;/div & gt php regular expression replacement, why cannot it be replaced?

PHP code

  

  

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  '; [B] // replace content $ local_replace_area [0] = 'replace _ area_1'; // cannot be replaced here? $ Patterns [0] = "/^

  [\ S \ S] *

  $/I "; // cannot be replaced here? [/B] $ page = preg_replace ($ patterns, $ local_replace_area, $ page); echo $ page;?>

------ Solution --------------------
$ Patterns [0] = "/^ [\ S \ S] * $/I "; // cannot be replaced here? [/B]

The last $ has a problem. it is not the end part of the string. how can I remove it?