The New York City subway returned to limited service Monday morning, a sigh of relief for those commuting to work. Parts of the underground system will remain closed due to flooding, including all service to the Rockaways on the Atlantic Coast in Queens. The morning rush hour will also be serviced by fewer trains. Service on suburban commuter trains is spotty, with Metro North and New Jersey Transit remaining totally closed and Amtrak canceling all service between Boston and Philadelphia. Departures will resume at 7 a.m. at LaGuardia Airport, and at noon at Kennedy and Newark Liberty International Airports. Full train service to upstate New York, Connecticut, and Long Island may take days to restore as many of the rails were hit with fallen trees and flooding.