Having lived in Vietnam for 6 years and studied Vietnamese at the University of Social Sciences and Humanities it never ceases to amaze me that if I speak and pronounce a Vietnamese phrase perfectly to most Vietnamese, they don't understand me. Every time I check out my groceries I say to the clerk, "Khỏe không?" after that is not understood, I say, "Em có khỏe không?", still no comprehension. About this time somebody in the line will say in a whisper, "Khỏe không?" and then the clerk repeats what I just said and apologizes. So I have asked numerous times if my pronunciation is clear or not? My instructor and everyone says I speak well, so what is that?? Even if a Vietnamese speaks to me in poor English, I understand what he/she said but it seems not to work the other way around. Some people say they must have thought I was speaking English; why would I speak English to a Vietnamese? I have a few theories but will be interested in others thoughts. It truly boggles the mind that more than half the population doesn't understand their own language if not spoken by a Vietnamese.