题目

－ Is your father in?                               － No, he ______ for three hours. A. was out B. has been out C. went out D. has gone out    答案：B11．图中 a 地区水土流失严重的原因有（　　）①土质疏松②植被覆盖率高③夏季多暴雨．A．①②B．①③C．②③D．①②③