90,30,12,6,4,()
A.4
B.2
C.6
D.7
1 2 3 4 () 9 8 12 18 27 A.6 B.7 C.10 D.11
90,30,12,6,4,() A.4 B.2 C.6 D.7
2,4, 6, 12, 14, (‘)A.20 B.24 C.28 D.30
2/3 ,1/2 ,5/9 ,(),11/15 A.2/5 B.6/11 C.3/4 D.7/12
8,4,4,6,12,30,() A.45 B.60 C.90 D.120
[(9,6)42(7,7)][(7,3)40(6,4)][(8,2)()(3,2)] A.30 B.32 C.34 D.36