Sentence:  `` Now that Bruno Walter <WSD>is</WSD> virtually in retirement and my dear friend Dimitri Mitropoulos is no longer with us , I am probably the only one - with the possible exception of Leonard Bernstein - who has this special affinity for and champions the works of Bruckner and Mahler '' . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)