若多项式x2+ax+8 和多项式x2 ﹣3x+b 相乘的积中不含x2 、x3 项，求（a ﹣b ）3 ﹣（a3 ﹣b3 ）的值．
解：﹣18．
— Look at the sign on the right.
— Oh, parking here.
A．isn’t allowed
B．doesn’t allow
C．wasn’t allowed
D．is allowed
氟氯烷烃
A．油质性基质B．水溶性基质C．栓剂基质D．乳化剂E．气雾剂的抛射剂
