http://www.irs.gov/pub/irs-pdf/p515.pdf
quote: (page 23第一段)
"Example: Article 20 of the U.S.-China income tax treaty allows an exemption
from tax for scholarship income received by a Chinese student temporarily
present in the United States. Under the Internal Revenue Code, a student may
become a resident alien for tax purposes if his or her stay in the United
States exceeds 5 alendar years. However, the treaty allows the provisions of
Article 20 to continue to apply EVEN AFTER the Chinese student becomes a
resident alien of the United States."
请不要再问了。