State and federal regulators have just three weeks to green-light deals that will keep St. Elizabeth's Medical Center in Boston and five other hospitals open. State Attorney General Andrea Joy Campbell's office has already finished its review and given its assent to the sales of St. Elizabeth's and five other hospitals: Good Samaritan Medical Center in Brockton, St. Anne's Hospital in Fall River, Morton Hospital in Taunton, and Holy Family Hospital with campuses in Methuen and Haverhill. But the deals still are subject to review by the state Department of Public Health, the state Health Policy Commission, the US Department of Justice, and the FTC in a compressed timetable dictated in large part by the hospitals' precarious finances.