Exercises for indefinite articles a or an

Choose "a" or "an" from the list.

  goose is bird.  
  duck is bird.  
  Robert is uncle.  
  carrot is fruit.  
  Football is game.  
  The Thames is river.  
  tomato is fruit.  
  rose is flower.  
  This taxi is old car.  
  This book is exercise book.  
  A hammer is tool.