Grammar / Conditional Sentences
Conditional Sentences: Explanation, Examples & Exercises
Conditional sentences describe a condition and its result: If it rains, we'll stay in. English has a zero conditional for facts, a first for real future possibilities, a second for unreal or unlikely present situations, and a third for imagined past ones — and each type takes a specific verb pattern in the if-clause and the result clause.
Reviewed by Brando Oxley · 9 Aug 2026
Form
Zero conditional (general truths): If + present simple, present simple — If you heat water, it boils.
First conditional (real future possibility): If + present simple, will + base verb — If I finish early, I'll call you.
Second conditional (unreal / unlikely present or future): If + past simple, would + base verb — If I had more time, I would learn the piano.
Third conditional (imagined past): If + past perfect, would have + past participle — If we had left earlier, we would have caught the train.
The if-clause can come first or second. When it comes first, separate the two clauses with a comma: If you ask, they'll help. They'll help if you ask.
In the second conditional, were is often used for all subjects after if: If I were you, I'd take the job.
How it is used
Zero conditional: things that are always true — facts, rules and habits: If the light is red, you stop.
First conditional: a real, likely situation and its probable result: If the client agrees, we'll sign tomorrow.
Second conditional: something unlikely, imaginary or contrary to the present facts, and for polite advice: If I won the lottery, I'd travel the world. If I were you, I'd rest.
Third conditional: looking back at the past and imagining a different result — often regret or criticism: If I had studied harder, I would have passed.
Common errors
✗If it will rain, we will stay home.
✓If it rains, we will stay home.
Don't use will in the if-clause of a first conditional; use the present simple.
✗If I would have time, I would help.
✓If I had time, I would help.
The second-conditional if-clause uses the past simple, not would.
✗If she had asked, I would helped her.
✓If she had asked, I would have helped her.
The third-conditional result is would have + past participle.
✗If you heat ice, it will melt.
✓If you heat ice, it melts.
For a general fact (zero conditional), both clauses are present simple.
✗If I was you, I would take the offer.
✓If I were you, I would take the offer.
In this fixed advice pattern, were is used for all subjects.
Example sentences
Zero and first (real)
- If you press this button, the machine stops.
- If the report is ready, I'll send it today.
- We'll miss the flight if we don't leave now.
Second (unreal present)
- If I had more time, I would take a course.
- If I were the manager, I'd change the schedule.
- She would travel more if she had the money.
Third (imagined past)
- If we had booked earlier, we would have saved money.
- I would have called you if I had known.
- If he had listened, he wouldn't have made that mistake.
Exercise 1 — Fill the gaps
Complete each sentence, then tap to check your answer.
1.If you heat water to 100°C, it ·.(boil — zero conditional)
2.If the client agrees, we · the contract tomorrow.(sign — first conditional)
3.If I · more time, I would learn another language.(have — second conditional)
4.We would have caught the train if we · earlier.(leave — third conditional)
5.If I · you, I'd take the job.(be — advice pattern)
6.If it · tomorrow, we'll stay at home.(rain — first conditional)
7.She would have helped if she · about the problem.(know — third conditional)
Exercise 2 — Choose the correct form
Tap an option to check it immediately.
1.If it ____ tomorrow, we'll cancel the picnic.
2.If I ____ more money, I would buy a bigger flat.
3.If we had left earlier, we ____ the meeting.
4.If you ____ ice, it melts.
5.If I ____ you, I'd apologise.