Sentence:  Measurements at 3.15 cm <WSD>were</WSD> obtained on 11 days spread over the interval May 3 to June 19 , 1956 , using the 50 - foot reflector at the U.S. Naval Research Laboratory in Washington . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)