下列关于东北三大农业生产区域的分布及组合,不正确的是( )
A:耕作农业区﹣﹣松嫩平原、三江平原、辽河平原
B:林业和特产区﹣﹣大小兴安岭和长白山区
C:畜牧业区﹣﹣西部高原、松嫩平原西部及部分林区草地
D:舍饲养畜业﹣﹣广大林区和农区
—Sorry. There isn't ________ left in the fridge.
—How about joining us in the summer camp?—I wish I could, ___________ I have to practice for the piano test.
若一个多边形内角和为900°,则这个多边形是 ____边形.