Sentence:  That exchange <WSD>was</WSD> not only possible but commonplace last week in Manhattan , as more and more New Yorkers were discovering 29 th Street and Eighth Avenue , where half a dozen small nightclubs with names like Arabian Nights , Grecian Palace and Egyptian Gardens are the American inpost of belly dancing . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)