提公因式法下列各式得公因式是a得是( )ax+ay+5 B.3ma-6ma2 C.4a2+10ab D.a2-2a+ma-6xyz+3xy2-9x2y的公因式是( )-3x B.3xz C.3yz D.-3xy把多项式(3a-4b)(7a-8b)+(11a-12b)(8b-