Sentence:  The convertible debentures <WSD>are</WSD> convertible into common shares at $ 65 a share by June 1 , 1966 ; $ 70 by 1971 ; $ 75 by 1976 ; $ 80 by 1981 ; $ 85 by 1986 , and $ 90 thereafter . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)