The server then receives, from a client, a request for an advertisement to display to the first user, selects one of the other users having a friend rank satisfying a predetermined threshold, and transmits, to the client, {HEAD ~ an advertisement} portraying {TAIL ~ the selected additional user} 
portraying
The server then receives , from a client , a request for an advertisement to display to the first user , selects one of the other users having a friend rank satisfying a predetermined threshold , and transmits , to the client , { HEAD ~ an advertisement } portraying { TAIL ~ the selected additional user }
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