Sentence:  As Brother John Sellers sang five `` blues '' to the guitar and drum accompaniments of Bruce Langhorne and Shep Shepard , Mr. Ailey and Miss De Lavallade went through volatile dances that <WSD>were</WSD> by turns insinuating , threatening , contemptuous and ecstatic . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)