Formula
If + present simple → present simple
Zero Conditional
Use the Zero Conditional to describe facts, rules and general truths. Both clauses stay in the present simple because the result is always true when the condition is true.
When do we use it?
- General facts & scientific truths: If you heat ice, it melts.
- Instructions: If the phone rings, answer it.
- Fixed schedules / rules: If Monday is a holiday, we close the office.
- Result clauses starting with when, unless, whenever etc.
Syntax details
Swap the clauses freely:
If the sun rises, the sky gets bright. The sky gets bright if the sun rises.
Comma only when the if‑clause comes first.
Affirmative, Negative & Question
| Form | Structure | Example |
|---|---|---|
| Affirmative | If + V1 … , V1 |
If you press start, the machine runs. |
| Negative | If + do not V1 … , do not V1 |
If you don’t water plants, they die. |
| Question | What happens if + S + V1 … ? |
What happens if metal gets hot? |
More examples
- If cats are hungry, they meow.
- If water reaches 100 °C, it boils.
- If people exercise, their heart rate increases.
- If you mix red and blue, you get purple.
- If public transport is late, commuters get frustrated.
- If the alarm goes off, leave the building immediately.
Watch out for these mistakes
- Don’t add “will” in either clause.
❌ If youwill heatice, it melts.
✅ If you heat ice, it melts. - Keep both verbs in the present simple, even when talking about future results.