11.  The reasons of these changes is mainly about the developments of the economy and the service of hospital.

12.  And the development of the service in hospital Decrease the infant mortaility .

13.  They also can know it through porpulur medieur , service for society, and so on.

14.  Sencond , we could know it from society service.

15.  Such as mediums of public, sociate service.

16.  Meanwhile, we also learn about a company, a enterise , even a store, by means of sociate service.

17.  There are many kinds of ways, such as the people medium, society services and so on.

18.  And what's more, free society services performed by us can give us directly sensations about the society.

19.  Second, you also can know the world through public stadium or society service.

20.  Take , for example, we can know the society through society's service, or several medium .