Sentence:  I mean something more like Freud 's concept of the utility of `` play '' to a small child : he plays `` house '' or `` doctor '' or `` fireman '' as a way of mastering slightly frightening experiences , reliving them imaginatively until they <WSD>are</WSD> under control . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)