• When to Omit the By Phrases

• 
• Not all passive voice sentences need a by phrase.  A by phrase is not needed if it does not add important information to the sentence. 

  
  

  -The Internet is used by many people worldwide.(Not important) 

  -The Internet is used worldwide.

  
  

  Always use a by phrase when it adds important information to the sentence or if you cannot understand the sentence without it.

  
  

  -The Harry Potter series was written by J.K. Rowling. (Important)

  -The Harry Potter series was written.
•  Click on the play button to hear the audio

• Three cars are parked in front of my house.	The book was published in September.
  This restaurant is owned by Gordon Ramsay.	These dresses were designed by Christian Dior.

 Source : Alison