The president knows that he will not be elected again because he has ________ too many of his promises.
句意: 总统知道他因为背弃了太多的诺言, 不会再次当选。 go back on背离(诺言、 协议等) 。 give up放弃。 come up with提出; 想出。 put on穿戴; 涂抹(化妆品) ; 举办(演出、 展览) ; 提供(服务) 。 pull out从……退出; 撤离。根据句意可知, 正确答案为B。