Sentence:  Assuming the weather <WSD>is</WSD> halfway decent that day , hundreds of thousands of persons will mass along this thoroughfare as President John F. Kennedy and retiring President Dwight D. Eisenhower leave Capitol Hill following the oath-taking ceremonies and ride down this historic ceremonial route . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)