听力原文： The campaign for Iran's June 8 presidential election officially is underway.
The interior ministry in Tehran on Friday authorized the 10 candidates, approved by the conservative Guardians Council, to begin their campaigns.
State media say reformist President Mohammad Khatami is almost certain to win a second four-year term. But President Khatami faces a slate of mostly conservative candidates who could erode his mandate to continue economic and social reforms.
Iran's Supreme Leader Ayatollah Ali Khamenei has not endorsed any of the candidates, but has urged eligible voters to cast ballots. Some 42 million people over the age of 15 are eligible to vote.
Iran's election laws require the campaign to end 24 hours before the first votes are cast. Candidates may no! use campaign buses with loudspeakers, but may make public speeches with prior approval from the interior ministry.
How many candidates were authorized by the interior ministry?