: http://qingtianwy966.blog.163.com/blog/static/204021238201252875011250/
: 8-9
:
(100% , 240 /50 ) - 50 , 10 , 2.
. . , + 3 . 1. 21 3 , 3 3 . . , 1 . /. 2 1 , 1 1 . 6 , 1 .
: 1 . / 1 «». 4 (. ).