There are three types of polio virus.
VOA: special.2010.01.18
Hundreds of thousands of people used to get polio, a virus that spreads as easily as the common cold.
VOA: standard.2010.08.02
For Zak Ahmad, just one week after getting polio, his immune system began to fight the virus.
VOA: standard.2010.08.02
应用推荐