：what are you doing now?？：

actually, what our international friend meant hear is that the kind of the intonation used in expressing this sentence is not polite, and there is a better way to show the speaker's way of greeting the friend.
the sentence "what are you doing" is spoken not in a native way, i mean the speaker do not truly understand the kind of culture perched on this line of words(it is a little Chinglish culturally speaking, similar to "Have you eaten?")--our international friends are individuality-oriented. what they are doing seems to them something personal and private and significant to them, and really has nothing to do with the speaker. culturally speaking, it is something similar to "what is your salary","how old are you""are you married", and the like.