came from our video on worker. It's when do  I know to pronounce or as er. General rule  

is that or is at the end of a word  we are going to pronounce it as er  

and you would see this in the word doctor. You  also may pronounce ar at the end of the words  

again as an er, as the er , and that would be  in the word dollar. And then er at the end of  

the word you pronounce it as er as well in anger.  So again we have doctor dollar anger good luck!