PHP form with two <select> variable passing as one

i have a form, say a.php, with

<select 1>var1...</select>
<select 2>var开发者_Python百科2...</select>

for some reason, i really want to pass those two variables as just one as

a.php?a=var1_var2

i don't know how to make it work.

thanks a lot.

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Just pass them individually and later concatenate to your desired valued.

<?php
var a = $_GET["var1"].$_GET["var2"];
?>

and call as:

a.php?var1=val1&var2=val2