<?php
 
$str = '
<font color="maroon">[como]</font>  &lt;rel&gt; &lt;ks&gt; <font color="blue"><b>ADV</b> </font> <font color="darkgreen">@ADVL&gt;</font> <font color="darkgreen"><b>@#FS-ADVL</font></b> <font color="darkgreen"><b>@#FS-N&lt;</font></b>
    <dt><b><font color="maroon">não</font></b> 
 
    <font color="maroon">[não]</font>  <font color="blue"><b>ADV</b> </font> <font color="darkgreen">@ADVL&gt;</font>
    <dt><b><font color="maroon">amar</font></b> 
 
    <font color="maroon">[amar]</font>  &lt;vt&gt; <font color="blue"><b>V</b> FUT 1/3S SUBJ VFIN </font> <font color="darkgreen">@FMV</font>
    <dt><b><font color="maroon">uma</font></b> 
 
    <font color="maroon">[um]</font>  &lt;arti&gt; <font color="blue"><b>DET</b> F S </font> <font color="darkgreen">@&gt;N</font>
    <dt><b><font color="maroon">pessoa</font></b> 
 
    <font color="maroon">[pessoa]</font>  &lt;H&gt; <font color="blue"><b>N</b> F S </font> <font color="darkgreen">@&lt;ACC</font>
    <dt><b><font color="maroon">tão</font></b> 
 
    <font color="maroon">[tão]</font>  &lt;dem&gt; &lt;quant&gt; <font color="blue"><b>ADV</b> </font> <font color="darkgreen">@&gt;A</font>
    <dt><b><font color="maroon">linda</font></b> 
 
    <font color="maroon">[lindo]</font>  <font color="blue"><b>ADJ</b> F S </font> <font color="darkgreen">@N&lt;</font>
    <dt><b><font color="maroon">.</font></b>';
 
$regex ='/\[.*\]/';
preg_match_all($regex, $str, $matches);
 
echo '<pre>';
print_r($matches);
 

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