Sentence:  Since accurate base maps <WSD>are</WSD> necessary for any planning program , the first step taken by the planning division to implement the long range state plan has been to prepare two series of base maps - one at a scale of 1 inch to a mile , and the second a series of 26 sheets at a scale of 1 inch to 2000 feet , covering the entire state . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)