Sentence:  One finds , for example , that a terse and stereotyped verbal expression , seeming at first to <WSD>be</WSD> a mere hollow convention , reveals itself over the months of therapy as the vehicle for expressing the most varied and intense feelings , and the most unconventional of meanings . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)