Opposite to show position or location - 
      The bank is opposite the supermarket
      The park is opposite the river
      The school is opposite the playground
               ******** In these examples you do not have a preposition  (of, from, to, etc)  
                               
 
 
Opposite to show difference - 
      Light is opposite "of" dark
      Good is opposite "of" bad
      Yes is opposite "of" no
               *********** In these examples you have the preposition "of" to indicate a comparison showing difference 
(In incorrectly said "article" earlier.  Totally stupid on my part. I truly meant preposition. I was in the middle of preparing a beginner lesson about articles at the time and my fingers and brain were not  communicating. I�m so sorry)