With everyone gone elsewhere, Earth was perfect for gracious living—only there was nothing gracious about it! he red tennis robot scooted desperately across the court, its four wide-set wheels squealing. For a moment, Robert's hard-hit passing shot seemed to have scored. Then, at the last instant, the robot whipped around its single racket-equipped arm. Robert sprawled headlong in a futile lunge at the return. "Game and set to Red Three," announced the referee box from its high station above the