听力原文： Under growing international pressure, U.S. authorities Tuesday seized a Cuban exile accused by Fidel Castro's government of masterminding a 1976 airliner bombing that killed 73 people. He had been seeking asylum in the United States. Luis Posada Carriles, a 77-year-old former CIA operative and Venezuelan security official, was taken into custody by U.S. immigration authorities, the Homeland Security Department said in a statement. The department did not say what it planned to do with Posada. Venezuela has asked for his extradition, and Cuba has asked that he be sent to Venezuela for retrial in the bombing or go before an international tribunal. Generally, the U.S. government does not return people to countries acting on Cuba's behalf, the department said. It has 48 hours to determine his immigration status. Luis Posada Carriles was detained______