为什么有些汉字用正则替换会出现乱码，是什么原因导致的呢？

Question

// \s  匹配任何空白字符，包括空格、制表符、换页符等等。等价于 [ \f\n\r\t\v]。注意 Unicode 正则表达式会匹配全角空格符。
echo preg_replace('/[ \f\n\r\t\v]+?(\S+)?$/', '', '加强和改进党的作风'); //会有乱码
echo '<br>';
echo preg_replace('/[ \f\n\r\t\v]+?(\S+)?$/', '', '加强和改进共的作风'); //会有乱码
echo '<br>';
echo preg_replace('/[ \f\n\r\t\v]+?(\S+)?$/', '', '加强和改进你的作风'); //没有乱码
echo '<br>';
echo preg_replace('/[ \f\n\r\t\v]+?(\S+)?$/', '', '加强和改进他的作风'); //没有乱码

很奇怪，用某些字会有乱码，换成其他汉字又没有乱码。

都是utf-8的字符，是什么原因导致的意外乱码呢？

Answer 1

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

Answer 2

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

Answer 3

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

Answer 4

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