题目

毛.泽东宣告：“中国人民从此站起来了”这表明我们          A已经结了被侵略被奴役的历史                B 民主革命的任务已经完成          C 中国已经进入了共产主义社会                D社会主义制度已经建立 答案：B －Did you find the missing couple in the mountain yesterday? －No, but we ________ to get in touch with them ever since． [　　] A．have tried B．have been trying C．had tried D．had been trying