Sentence:  Watch people flock to amusement houses , cocktail lounges , and night clubs that advertise continuous entertainment , which means an endless flow of noise and frivolity by paid entertainers who <WSD>are</WSD> supposed to perform in those incredible ways which are designed to give men a few hours of dubious relaxation - watch them and you can tell that many of them are running away from something . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)