    Sentence 1: The U.S. government and  rivate technology experts _ warned  Wednesday that hackers plan to attack  thousands of Web sites Sunday in a  loosely co-ordinated " contest " that  could disrupt Internet traffic .    Sentence 2: THE US government and  rivate technology experts have warned  that hackers plan to attack thousands of|  websites on Sunday in a loosely co-  lordinated " contest " that could disrupt  Internet traffic .