Zero Conditional

¿ When to use zero conditional?
  
we use the so called zero conditional when the result of the condition is always true, like a scientific fact.

estructura

IF + present simple, ---- present simple
If       it rains,                   i get wet
 
ejemplos:

If you freeze water, it turns into ice.

If I work too much, I get tired. 

If I have time, I usually go to the movies.

If she eats hamburgers, she gets an allergy.

If they come here, they always bring a present.