Sentence:  Again , I at first misconstrued this disconcertingly intense communication , and I quickly cast through my mind to account for her <WSD>being</WSD> able to speak , with such utter conviction , of an opinion held by my father , now several years deceased . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)