Many study abroad programs are well established — the American Field Service (AFS) student exchange program has been been around for more than 50 years.

很多留学项目都十分可靠，像美国战地服务团（AFS），它们的留学交换项目已经有五十多年的历史了。

It cited statistics from the student and Exchange Visitor Program, a Department of Homeland Security unit that tracks foreigners in the US on student visas and the schools they attend.

数据援引自国土安全部中负责中学生和交流访问者项目的一个部门，这个项目跟踪外国人在美国的学生签证和学习学校的统计数据。