Sentence:  Anatomically , the horse lung appears to <WSD>be</WSD> remarkably like that of man , insofar as this can be ascertained from comparison of our findings in the horse with those of others ( Birnbaum , ' 54 ) in the human being . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)