Usar "muss" en una oración

1. And still later, when Ingeborg had left off pretending or trying to be anything at all, when courage and unselfishness and stoicism and a desire to please Robert--who was Robert?--were like toys for drawing-room games, shoved aside in these grips with death, Frau Dosch nodded her head philosophically while she ate and drank from the trays Ilse kept on bringing her, and said at regular intervals, "_Ja, ja_--was sein muss sein muss

2. And then he shouted that man muss pay him fifteen roubles damages