Overview
Express general truths, scientific facts, and automatic results using if/when + present simple in both clauses.
Zero conditional structure
- structureIf/When + present simple, present simple
- exampleIf you heat water, it boils.
- with 'when'When you don't sleep, you feel tired.
- general factPlants die if they don't get water.
Uses
- Scientific facts: If you heat metal, it expands.
- General truths: If you don't eat, you get hungry.
- Instructions: If the alarm rings, leave the building.
- 'When' can replace 'if' when the event is certain.
Common Mistakes
- ❌ If you heat water, it will boils. → ✅ it boils. (no 'will')
- ❌ When you will exercise, you feel better. → ✅ When you exercise …
- ❌ If it rains, we stayed inside. → ✅ If it rains, we stay inside.
When to use
Science
If you mix blue and yellow, you get green.
Instructions
If the screen freezes, restart the device.
Nature
When the temperature drops, water freezes.
Teaching facts
If you add salt to water, the boiling point rises.