Psychologists suggest that to cure cruelty

Priestly called the new material rubber,

1. 
   as was instructed by his American friend
   
2. 
   because it was soft and could easily be rubbed
   
3. 
   since he had shaped the ball by rubbing it on a hard surface
   
4. 
   having been inspired by one of its functions
   

2. If rubber had not been discovered

1. 
   people would have to use synthetic substitutes instead
   
2. 
   there would not be any shoes, chairs, or gloves
   
3. 
   people would be even less imaginative than they are now
   
4. 
   life today would be considerably different from what it is
   

3. At present, there are many types of products made from rubber,

1. 
   though it seems that many are being replaced by plastics
   
2. 
   and it seems quite likely that there will be more in the future
   
3. 
   despite the fact that the material tends to wear out quickly
   
4. 
   but people tend to stay away from the material and use natural substitutes instead