But welcoming foreign students does not require giving them an effectively open-ended right to remain in the country. Most temporary visitors admitted to the U.S. receive a specific date by which they must leave or obtain permission to remain longer. An institution collecting tuition from a foreign student, for example, may have little incentive to scrutinize prolonged enrollment. But requiring an alien periodically to demonstrate eligibility for temporary immigration status is not an attack on international educational exchanges. Congress did not create the foreign student and exchange visitor programs as entitlement to long-term residency in the United States.