听力原文： The United States has begun to review Russian documents about the life and death of former President John F. Kennedy and expected to release them once the review is complete, the White House said on Monday. The documents which Russia gave the United States on Sunday could be a particular interest because Kennedy's assassin Lee Harvey Oswald lived in the former Soviet Union for several years before he returned to the United States and was arrested for killing the former President on November 22nd, 1963. Russian President Boris Yeltsin surprised US president Bill Clinton on Sunday when he turned over what was described as the results of an exhausted search of Russian government, military and private archives for papers about Kennedy and his assassination. The Russian documents are expected to draw great attention because