conditional type 0 >> ZERO CONDITIONAL |

IF + SIMPLE PRESENT + SIMPLE PRESENT
Used for scientific facts or general truths (usado para expresar verdades científicas, hechos que nunca cambian o situaciones que siempre ocurren). Algunos gramáticos incluyen este tipo de condicional dentro de FIRST CONDITIONAL o Conditional Type I. | If you heat butter, it melts.
Si calientas manteca, ésta se derrite. | If you put water in a cooler, it freezes.
Si colocas agua en el congelador, ésta se congela. | If you heat water to 100 degrees, it boils.
Si calientas agua a 100 grados, ésta hierve. | If you cross an international date line, the time changes.
Si cruzas una línea de tiempo …ver más…

| The real situation was that you didn't save your money. So they say If you had saved... When you are talking about the past, you use the Past Perfect (I had known) after IF. | If you hadn't been late for work so often, they wouldn't have fired you.
Si no hubieses llegado tarde al trabajo tan seguido, no te habrían despedido. |

The real situation was that you wasn't early for work. So they say If you hadn't been late... When you are talking about the past, you use the Past Perfect (I had known) after IF. |

NOTE: You can replace IF (si) by UNLESS (a menos que) in the examples above.