Proxy for GNUS

[Ying Zu]

Now I can only get access abroad by http proxy, while surfing free in my own 
country.
But when I opened gnus, I found that it can retrieve groups and show posts as 
usual except for a
little slow, maybe for the connection via proxy. 
But I didn't set particular proxy for gnus, though my firefox's keeping 
connection via a valid
proxy.
I wonder whether gnus utililize the browser http setting on its own?
And, Is there a chance I can set in the gnus?
Thanks! :)