تعلم الانجليزية: Polio Vaccine 50th Anniversary
This is Robert Cohen with the VOA Special English Development Report. Fifty years ago, no one knew how to stop polio . Polio is a disease o...
تعلم الانجليزية: Polio Vaccine 50th Anniversary
This is Robert Cohen with the VOA Special English Development Report. Fifty years ago, no one knew how to stop polio . Polio is a disease o...
