【正确答案】 C

【答案解析】call off: 停止，取消。cancel：取消。Why was the baseball game cancelled yesterday?为什么昨天的棒球比赛取消了?put off: 推迟。They decided to put off the meeting until after Christmas．他们决定会议推迟到圣诞节后举行。end：结束。The government acted to end a bakers’ strike in the city．政府采取行动结束城里面包师傅的罢工。participate in: 参加。Did you participate in the discussion?你参加讨论了吗?