听力原文: A young woman who wanted to leave a cruise ship to return to her boyfriend in California spent Monday night in a federal imprisonment center here, charged with threatening to kill everyone aboard the ship to cut the cruise short. The cruise ship was on a 10-day trip out of Ensenada, Mexico, when crew members found two handwritten notes on April 22 and 2Both notes stated that if the ship docked in a US port, the nearly 2,400 passengers and crew would all die. When the ship was searched, nothing was found. The cruise resumed on April 24. The woman herself confessed the following day. Why was the young woman held up in the federal imprisonment center?