What are the linking verbs?
The role of the linking verbs is to connect the subject to other information. The infinitive of the linking verbs are ‘to be’, ‘to seem’ and ‘to become’, and some forms of these verbs are, ‘is being’, ‘seemed’ and ‘will become’.You can find more information here: http://www.yourdictionary.com/grammar-rules/Linking-Verbs.