Sentence:  Data on the former <WSD>are</WSD> scanty , but there can be little doubt that the latter is sometimes born at a length greater than that of any of the others , thereby lending support to the belief that the anaconda does , indeed , attain the greatest length . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)