0,1/9,2/27,1/27,()。
A.27
B.7/9
C.5/18
D.4/243
1/9,2/27,1/27,() A,4/27;B,7/9;C,5/18;D,4/243;
0,1/9,2/27,1/27, ()A.27 B.7/9 C.5/18 D.4/243
5, 3, 7, 9, 15, 23, ()。A.27B.31C.35D.37
0,1/9,2/27,1/27, () A.27 B.7/9 C.5/18 D.4/243
4,5,15,6,7,35,8,9,()A.27B.15 C.72D.63