单项选择题
A.4, 5, 6, 1, 2, 3, B.1, 2, 3, 3, 2, 1, C.1, 2, 3, 4, 5, 6, D.6, 5, 4, 3, 2, 1,
A.42 B.0 C.1 D.41
A.1 2 5 6 B.5 6 3 4 C.5 6 1 2 D.3 4 5 6