Help me with an url rewrite

[suppressed]

I'm not sure if I've asked the correct lists,but hope I can get some 
helps here.:)

I need a mod_rewrite rule,rewrite this url:
http://abc.site.com/index.php?q1=v1
to:
http://www.site.com/index.php?q1=v1&domain=abc

I applicated this rule:

   RewriteEngine on
   RewriteRule   ^/(.+)$  http://www.site.com/$1&domain=abc


But I'm faint I can't get the correct result,it rewrote the url to:

http://www.site.com/index.php&domain=abc?q1=v1

(not http://www.site.com/index.php?q1=v1&domain=abc)

This disorder the things,I do hate it.

Can you show me a correct way?thanks.
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