Sentence:  At 4 p. m. the President left the White House to welcome the young musicians , students from the ages of 12 to 18 who spend six weeks at the Brevard Music Center summer camp , and to greet the 325 crippled , cardiac and blind children from the District area who <WSD>were</WSD> special guests at the concert . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)