2019N 1
y
 
 
1
xf
2
~Gx
3
~Gx
4
5
6
xf
7
8
xf
9
10
11
12
13
14
xf
15
xf
16
17
18
19
20
21
22
xf
23
24
25
26
27
xf
28
29
xf
30
31