A:was staying
B:stay
C:stayed
D:am staying
通过下列哪一事件,中国农民实现了千百年来“耕者有其田”的梦想( )
设集合S=1,2,3,4,5,6,7,8,9,集合A=a1,a2,a3,A⊑S,a1,a2,a3满足a1<a2<a3且a3-a2≤6,那么满足条件的集合A的个数为( )
如图是动植物细胞结构模式图,请据图回答问题: