They think       important to look right and left when        the road.

A．it’s; cross

B．it; to cross

C．it’s;crossing

D．it was; to cross

已知函数f(x)=-x³+ax²+bx+c图像上的点P(1，-2)处的切线方程为y=-3x+1．
(1)若函数f(x)在x=-2时有极值，求f(x)的表达式．
(2)函数f(x)在区间[-2，0]上单调递增，求实数b的取值范围．