回复：为什么呢?哪里有详细的条例?

this is an issue of debate. I have done quite a lot of research on that but so far I haven't found any publication that specifically says you can or you cannot have std and treaty at the same time.

The only thing I am aware of is
1. stp's email from irs supporting "you can" (see up in the same thread)
2. UT austin int'l office tax guide that supports "you cannot":
UT austin
see "b".

So take it at you own risk. If you are going to file 485 within the next 3 years, you probably should play it safe.