半坡氏族和河姆渡氏族遗址都在大河流域,是因为( )
A:战略地位重要
B:水源丰富、土地肥沃、适宜农业生产
C:适宜航行、交通便利
D:环境优美
—Yes,I have.It was written by a celebrated writer,Yan Geling.