不需要提及绿卡的事情。
给你一个模板吧。
Dear Sir or Madam:
This letter respectfully requests a waiver for the 2-year home residence
requirement based on 'No Objection Letter' that will be obtained from my
home country (P. R. China). The reasons I would like to apply for a waiver
are the followings:
I have been in the U.S.A. since xxx and received my Ph.D. degree from xxx
University in xxx. I am currently employed as a xxx at xxx University. I am
not being funded by the United States or Chinese government, or any
international organization.
I specialize in the field of xxx.
Dr. xxx will sponsor me for this additional period before returning to China
. This will enable me to complete my current project as well as accept
additional training prior to beginning my independent academic career in
China.
I will apply for the No Objection Letter and my embassy will directly
provide you with the 'No Objection Letter' issued for me.
I appreciate your support and assistance for waiving my two-year home
country residence requirement.
Sincerely,