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http://huixin980603.blog.163.com/blog/static/2221710822014112671831211/
http://huixin980603.blog.163.com/blog/static/222171082201521065820161/
« 2x2» , , 2 .
1- : 2 , 4 - .
2- : .
3- : 3 , 2 , * 4, 2 , , *, 3 1 .
5- : .

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