Can

Can is used to show ability.  Can is a modal verb, and it
conjugates as follows:

Present	Past	Future
Can	Could	Will be able to

Can is used to show ability.

• I can play the piano.
  
• I could play the piano 10 years ago.
  
• I will be able to play the piano when I finish my piano class.
  

Can is used to make requests:

• Can you pass the salt please?
  
• Can you turn off the music?