foreach多层嵌套的问题，求解~！
<br />
<?php <br />
$a1=explode(',','20,21');<br />
$b1=explode(',','20,21');<br />
$c1=explode(',','20,21');<br />
$d1=explode(',','20,21');<br />
$e1=explode(',','20,21');<br />
foreach($a1 as $a ){<br />
<br />
foreach($b1 as $b){<br />
<br />
foreach($c1 as $c){<br />
<br />
foreach($d1 as $d){ <br />
<br />
foreach($e1 as $e){ <br />
<br />
}<br />
<br />
}<br />
<br />
}<br />
<br />
<br />
}<br />
<br />
}<br />
?><br />
<br />
foreach($a1 as $a ){<br />
echo $a;<br />
}<br />
foreach($b1 as $b ){<br />
echo $b;<br />
}<br />
