Sentence:  To be sure , in tool-and-die work and in the building trades , the first job must <WSD>be</WSD> often on an apprentice basis , but two years of halftime vocational training enables the young man thus to anticipate one year of apprentice status . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)