Sentence:  The unsatisfactory 1958 - 60 expansion , he said , <WSD>was</WSD> not due to inadequate growth forces inherent in our economy but rather to the adverse effect of inappropriate economic policies combined with retrenching decisions resulting from the steel strike . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)