东北地区是我国重要的农业生产基地,松嫩平原和三江平原是我国重要的商品粮生产基地。据此回答东北地区主要粮食作物和经济作物的分布情况是 A.北部有春小麦、大豆 B.中部有冬小麦、玉米和水稻C.中部有冬小麦、玉米和甜菜 D.南部有春小麦、棉花17.Zheng He is _____ great pioneer in exchanging cultures _____ Chinese people today still remember him.( )A.such a; thatB.so; thatC.too; toD.so; as to