&rt; 美國有硬性要求嗎？

有。
https://en.wikipedia.org/wiki/American_Indian_boarding_schools

&rt; Native American boarding schools, also known as Indian Residential Schools, were established in the United States during the late 19th and mid 20th centuries with a primary objective of assimilating Native American children and youth into Euro-American culture, while at the same time providing a basic education in Euro-American subject matters. These boarding schools were first established by Christian missionaries of various denominations, who often started schools on reservations, especially in the lightly populated areas of the West. The government paid religious orders to provide basic education to Native American children on reservations in the late 19th and early 20th centuries, with the last residential schools closing as late as 1973.

直到現在，印地安人還是沒辦法用自己的語文上課，只能用英文。