1. be at war with …在交战Ancient China was a place where states were often at war with each other. 古代中国各诸侯国之间经常发生战争。In 1920 Poland and Russia were still at war.在1920年,波兰和俄国仍在交战。 【知识拓展】 “at+不带冠词的名词” 表示“从事某种工作或处于某种状态”。 He is at work. = He is working. 他在工作。The family are at breakfast. =The family are having breakfast. 这一家人正在吃早饭。