Sentence:  For example , to move ( as the score requires ) from the lowest F major register up to a barely audible N minor in four seconds , not skipping , at the same time , even one of the 407 fingerings , seems a feat too absurd to consider , and it <WSD>is</WSD> to the flautist 's credit that he remained silent throughout the passage . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)