716o8
131oo131213
5o
13
OO@@
5
;
2s21s（?）
a2
b2s
c2
d2s2
c
cd2s22s2d
ab4
da=2s2da=4s2
x=at21s
cx=at21s2c
ba=vtv=at1sv=2x1s=2s1s2sab