Sentence:  Mr. Kennan , who has recently abandoned authorship for a new round of diplomacy as the recently appointed American ambassador to Yugoslavia , <WSD>is</WSD> not the only man who finds it easier to portray the past than to prescribe for the future . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)