The old man is used to playing ________ with his friend...

根据汉语提示‘中国象棋’，我们可以推测空格处需要填入‘xiangqi’，这是中国象棋的英文名。‘Xiangqi’是一个专有名词，表示中国传统的棋类游戏。句子‘The old man is used to playing ______ with his friends in the afternoon’中的‘playing’提示需要填入一个名词，‘xiangqi’符合语境，表示他和朋友们在下午下中国象棋。