Who are you w( ) for here,Jack?My Chinese friend from Beijin

答案是：waiting.
wait for sb------等某人
因为这里有who are you...中有are---就是说你正在等谁?
故要用进行时,那么wait的进行时就是：waiting.
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My Chinese friend from Beijing.----中的from Beijing是介词短语做后置定语
修饰friend.
即：my Chinese friend.就是一个人嘛
故,问对方正在等谁.
所以,填waiting.