Answer: 
    Oral poliovirus vaccine or Sabin vaccine, named for its inventor American physician and microbiologist Albert Sabin, was developed. OPV contains live attenuated (weakened) virus and is given orally.
 
        
             
        
        
        
It is true that cells spend most of their time dividing. In fact, they spend 78% of their "life" in interphase. 
        
                    
             
        
        
        
Answer:
At least 3 earthquake recording stations are required to find the location of the earthquake epicenter. A single recording station can only calculate distance, but not direction; to cover all possibilities, a complete circle is drawn around that station.
 
        
             
        
        
        
centromeres, in the synthesis phase