听力原文： Israeli Prime Minister Ariel Sharon and Secretary of State Colin Powell have agreed on a seven-day violence-free period to test a U-S-brokered cease-fire with the Palestinians. This would be followed by a cooling off period of six weeks and the introduction of measures to re-build trust between the two sides. Mr. Sharon and Mr. Powell announced an agreement between Israel and the Palestinians toward a resumption of peace negotiations. Appearing at a joint news conference, they said there must be a seven-day period of complete calm, followed by a cooling-off period. Mr. Sharon says he and Mr. Powell are completely in accord with the principle that the violence must stop before political progress can begin. How long will the cooling off period be according to the agreement between Israel and the Palestinians?