• Replacing Noun Clauses with So

• 
• When the answer to a question contains a noun clause, the answer can be shortened by replacing the noun clause with the word so after the verbs think, believe, guess, and hope. 

  
  

  - Are they filming a movie?

  - Yes, I believe that they are filming a documentary.

  
  

  Replace the noun clause with the word so.

  - Are they filming a movie?
  

  - Yes, I believe so.

• Do you think that there is a benefit to carpooling to work? - I think so.	Will all cars in the future be zero-emission electric vehicles? - I hope so.
  Is Greenpeace really making a difference with its social activism? - I guess so.	Are big corporations interested in helping the environment? - I don't think so.*

• *Be careful! For negative short answers, use I don't think so/I don't believe so for the verbs believe and think.  

  Use I hope not/I guess not for the verbs hope and guess. 

Source : Alison