你自己讀一下這段條約文字，看看你自己是否合格？

http://www.irs.gov/pub/irs-trty/china.pdf

ARTICLE 19
(Teachers, Professors and Researchers)

An individual who is, or immediately before visiting a Contracting State was, a resident of the other Contracting
State and is temporarily present in the first-mentioned Contracting State for the primary purpose of teaching, giving
lectures or conducting research at a university, college, school or other accredited educational institution or scientific research institution in the first mentioned Contracting State shall be exempt from tax in the first mentioned Contracting State for a period not exceeding three years in the aggregate in respect of remuneration for such teaching, lectures or research.


在控訴人家種族歧視前，要看看人家是否有道理。中國學者到美國講學進修的收入，不付美國稅。你們都已經有綠卡了，已經不符合“temporarily present"的條件，因為綠卡是“permanent residency".