下列问题中是古典概型的是( )
— Can you go to the mall tomorrow?
— I'm sorry I can't. I ____ (help) my sister with math.
如图,二次函数y=ax2+bx+c的图象交x轴于A(﹣1,0),B(2,0),交y轴于C(0,﹣2),过A,C画直线.