1 2

1

arerurareru

A B C N1/N2V 1/~~~

:12 N1. /N2V2

129

N1. /N2V3N

()

N

II ~~~

2 2 ~

2 N1 /N2N3(V""+"/ "" " "

123

N1 /N2/N3V4

//

12

3

N1 /N2N3V

""

a

13

2

3

b

11

2

~

~

~~~

1

2

1. 2.

II~~~~

3 --

1 2

1C P21522 B P2213 B P228