BE WARNED! This is a wolf in sheep's clothing.
In all fairness Mr shun Tang it'd be nice if you could mention that you have a webpage devoted to this topic and, moreover, with regards to professional courtesy, that you notify postees that their words will be copied and pasted without their consent onto said webpage as well as into the book you are presently writing.
Furthermore, given your history with the Applied Linguistics Board on Dave's ESL Cafe, postees should be warned ahead of time that Mr Tang has been tenaciously in search of the "Perfect" answer for the past 3 years and that his true goal here has nothing whatsoever to do with gaining a better understanding of the topic, but rather to find venue for his premise that native English grammarians conspire through their descriptions and definitions, such as the Present Perfect, to keep non-native speakers from actually attaining native like knowledge. :mad:
My apologies for speaking me peace. But, Mr Tang has a tendency to make people say things that stir up feelings inside of them that they particularly don't like.
- For Teachers