A student, business apprentice or trainee who is, or was immediately before visiting a Contracting State, a resident of the other Contracting State and who is present in the first- mentioned Contracting State solely for the purpose of his education, training or obtaining special technical experience
这里的 resident of the other contracting state 指的是中国居民吧。文件中有这个的定义：
For the purposes of this Agreement, the term “resident of a Contracting State” means any person who, under the laws of that Contracting State, is liable to tax therein by reason of his domicile, residence, place of head office, place of incorporation or any other criterion of a similar nature.
Where by reason of the provisions of paragraph 1 an individual is a resident of both Contracting States, then the competent authorities of the Contracting States shall determine through consultations the Contracting State of which that individual shall be deemed to be a resident for the purposes of this Agreement
全文没有提到任何visa或者I20等字眼，说只要你是中国的税务居民，就算是resident of the other contracting state。
但是中国是只要你户籍还在就算是税务居民，所以就符合resident of the other contracting state的标准。
然后因为中国规定出国定居或者加入外国籍（拿到绿卡算出国定居了吧）就应该注销户口（只是规定，实际执不执行是另一回事），所以绿卡拿到之前户口没注销都算resident of the other contracting state。
Paragraph 1 lists several criteria which may be used in domestic law to determine residence for tax purposes. Citizenship is not one of the criteria; thus a U.S. citizen resident in a third country is not treated as a U.S. resident for purposes of this Agreement. The reference to persons “liable to tax” is not meant to exclude organizations of either country which are tax-exempt under special provisions of its domestic law, such as charities. However, it would not include a person liable to tax only in respect of income from sources in the taxing country, such as a resident of a third country subject to tax in the United States or China only on a source basis.
Paragraph 2 provides that, where an individual is considered to be a resident of both Contracting States under their respective domestic laws, the competent authorities shall consult together to determine of which State the individual shall be a resident for purposes of the Agreement. In making that determination, the competent authorities will be guided by the rulesof paragraph 2 of Article 4 of the United Nation’s Model Double Taxation Convention between Developed and Developing Countries. (See Article 5 of the Protocol.) Those rules are the same as the rules contained in the corresponding paragraph of the OECD and U.S. Models. The first test is where the individual has his permanent home. If he has a permanent home in both countries the second test is where his personal and economic ties are closer (center of vital interests). If that test is inconclusive, or if the individual does not have a permanent home in either State, the next test is his place of habitual abode. The fourth test is nationality. If the individual is a national of both States or of neither of them, the competent authorities are instructed to settle the issue so as to assign a single State of residence. Once established under this article, the residence of the individual remains the same for all purposes of the Agreement。
是的。Article 20的technical notes完全没有任何关于immigration status的论述，就说“for the purpose of education, training or obtaining technical experience shall be exempt from tax”。我感觉只要是full time student，就可以继续用。之前用学校sprintax试验了一下把身份从F1换成Employment based，绿卡pending，结果sprintax依然告诉我可以claim treaty benefits
