Sentence:  Though no longer able to turn out his protoplasmic pen-and-ink sketches ( several old favorites <WSD>are</WSD> scattered through the present volume ) Thurber has retained unimpaired his vision of humor as a thing of simple , unaffected humanness . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)