About 45,000 workers at Verizon Communications from Massachusetts to Virginia have gone on strike after failing to reach an agreement on new contracts. The Communications Workers for America said Verizon was forcing workers to adopt far too many concessions, cutting health-care coverage and pensions. Verizon executives say the concessions are needed because of a long-term drop in revenue and profit. Striking workers include telephone field technicians, call center workers, and cable installers. Service delays are expected, although Verizon said it had trained tens of thousands of workers to replace those who went on strike.