Both translations are probably fine except you don't put (place) something in (on) first priority. This is not an expression in American English. Popular way is to "treat users and ad customers as our first priority".
Put "something" as first priority
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學習啦。Thanks!
-同學小薇-
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04/06/2012 postreply
16:30:00
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謝謝指正!
-tingfeng-
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04/07/2012 postreply
04:29:33