25 3 323 7 2008 6 2009X X X (3 7 2008) 6 20091 13 X 3 1 0 6X X 6
2)
b c
b
c
0
0.25
3
3
2
3
7
2008
6
2009
x
x
x
(3
7
2008) 6
2009
1
13
x
3
1 0
6
x
x
6