Frigates may improve defenses.Logical formLearned from2 sentences. Helicopters may operate off frigates.Logical formLearned from2 sentences. Frigates may be bought from a country.Logical formLearned from2 sentences. A frigate can be indigenous.Logical formLearned from2 sentences. A frigate may start.Logical formLearned from2 sentences. Exercises can be with (navy frigates).Logical formLearned from2 sentences. A (task force) may include a frigate.Logical formLearned from2 sentences. A frigate may stop for a visit.Logical formLearned from2 sentences. A (helicopter carrier) may be accompanied by a frigate.Logical formLearned from2 sentences. A group may consist of guided-missile frigate.Logical formLearned from2 sentences. A frigate can be acquired.Logical formLearned from2 sentences. A key man can be in arranging a sale of some frigates.Logical formLearned from2 sentences. Work may pertain-to frigates.Logical formLearned from2 sentences. A frigate may remain on standby.Logical formLearned from2 sentences. Frigates may pertain-to a guard-service.Logical formLearned from2 sentences.