• Zero Conditional

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• Use the zero conditional for facts, permanent truths, and habits. Zero conditional always uses present simple verbs.

  
  

  If + present simple, present simple.

  -If you heat ice above 0 degrees Celsius, it melts. (Fact)

  
  

  present simple + if + present simple
  

  Ice melts if you heat it above 0 degrees Celsius.

  
  

  In a zero conditional, the result of the if clause is always the same. It happens 100% of the time.
•  Click on the play button to hear the audio

• If I stay up too late, I am sleepy the next day.	If Pam doesn't eat breakfast, she is hungry by 10 AM.
  If a criminal is guilty, they go to prison.	The lake freezes if it snows overnight.

 Source : Alison