A:that were we…thi
B:that we were…that
C:if were we …thi
D:if we were…that
已知抛物线C1:y=ax2+bx+32(a≠0)经过点A(﹣1,0)和B(3,0).
两位数乘两位数的估算是通过把两数看成____、____的数来计算。