Sentence:  As we know , the Soviet peasant today still very largely thrives on being able to sell the produce grown on his private plot ; and it is still very far from certain how valid the party 's claim <WSD>is</WSD> that in `` a growing number of kolkhozes '' the peasants are finding it more profitable , to surrender their private plots to the kolkhoz and to let the latter be turned into something increasingly like a state farm . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)