2014-12-27 19:09
1517
0
·
1 21 20 18 15 11 —
A 4 B 6 C 8
2
A,120。B,135。C,
3
a b
a d d c
c
A,a B b C,c D d
4
A B C D
5
A
B C
D
6
A1 B 3C 5D 7E 11
F 13 G15 H17