单项选择题
A.k=6 a-1 B.k=3 a-14 C.k=4 a=12 D.k=5 a-15
A.a12xyz B.12yz C.a2yz D.bc2yz
A.2, 4, 8, B.3, 6, 9, C.3, 5, 7, D.1, 3, 5,