Sentence:  Sam Rayburn <WSD>is</WSD> one of the greatest American public figures in the history of our country and I consider that I have been signally honored in the privilege of knowing Sam Rayburn and sharing with him the rights and obligations of a Member of the House of Representatives in the Congress of the United States . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)