Sentence:  One sample , which had been exposed to the atmosphere after evacuation at 375 ` C , showed the presence of adsorbed water ( about 0.3 wt % ) as evidenced by a weak resonance line which <WSD>was</WSD> very narrow at room temperature and which disappeared , due to broadening , at low temperature . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)