If you heat water in a kettle, it boils. If you heat water in a kettle, it boils.
The zero conditional refers to real events. The result of the condition is always the same.
| Construction | Time reference | Example |
| 'if' + present, + present
| any time condition + any time result
| If the sun shines, people are happier. |
As with all conditionals, the 'if' clause can come first or second. When it comes first, it is followed by a comma.
Zero conditional sentences are used to talk about general truths and facts, not about individual, specific situations.
| Use | Examples |
| Scientific facts | If you add salt to water, it boils more quickly. |
| Universal truths | People put on weight if they eat too much. |
| Things that happen regularly | If I leave home at 8.00, I arrive at work at 9.00. |
Note that because the result is always the same, we can use 'when' as an alternative to 'if'. We also sometimes use 'whenever', especially for things that happen regularly:
If/when people don't drink, they get thirsty.
If/when/whenever he's late for work, his boss gets angry.
Present continuous
We can also use the present continuous:
If it's raining, people carry umbrellas.
If people are carrying umbrellas, it's probably raining.
Imperative
Whenever you're tired, take a break.
When I'm working, don't disturb me.
If you go to Paris, visit the Louvre.
Modals
Some modal verbs might be used in the main clause.
If you go to another country, you should try to speak the language.
You can get a refund if the plane is delayed.
=====Zero or first conditional?=====
The first conditional is used for real, likely events. Compare these two sentences:
If I leave home at 8.00, I arrive at 9.00. [this refers to every time I leave at 8.00]
If I leave home at 8.00, I'll arrive at 9.00. [this refers to a specific occasion in the future]
The alarm goes off whenever there's a fire.
Only children go in the garden if it's raining.
When you work with people from other countries, you might have to do things differently.
If she's eating then she's getting better. .
If you visit London, don't miss the Beefeaters at the Tower of London.