I'll spend as much time as I can _ in an old people's home.
A:help
B:to help
C:helping
如图,抛物线y=ax2+bx﹣3经过点A(2,﹣3),与x轴负半轴交于点B,与y轴交于点C,且OC=3OB.
如图是钾离子的结构示意图,从图中可以获得的信息是____
A.该元素的原子核内的中子数 B.该金属的物理性质
C.钾原子的最外层电子数 D.____