Conditionals 0, 1 & 2: if Sentences

1. Simple explanation

A conditional sentence joins two parts: a condition — a situation introduced by if (if means 'in the case that') — and a result, what happens because of the condition. English uses three main patterns: zero for facts that are always true ('If you heat ice, it melts'), first for real future possibilities ('If it rains tomorrow, we'll stay home'), and second for imagined, unreal situations ('If I were rich, I would travel the world').

2. Detailed explanation

Start from zero. A conditional sentence is a sentence with two parts, and it talks about a situation and its result. The first part is the condition: a condition is a situation that must happen first, before the second part can happen. The condition usually starts with the word if, and if means 'in the case that.' The second part is the result — what happens because of the condition. Look: 'If it rains, we stay home.' The condition is 'if it rains'; the result is 'we stay home.' No rain, no result.

English has three main conditional patterns in this lesson, and the pattern you choose shows how real the situation is. The zero conditional talks about facts that are always true: if + present simple, present simple — 'If you heat ice, it melts.' Use it for science, rules, and habits. The first conditional talks about a real possible future: if + present simple, will + verb — 'If it rains tomorrow, we will stay home.' The rain has not happened, but it really can happen. Notice: after if we use the present simple, never will. 'If it will rain' is wrong, because the will belongs in the result part, not in the if part.

The second conditional talks about imagination — situations that are not true now, or almost impossible: if + past simple, would + verb. 'If I had a car, I would drive to work.' In real life I do NOT have a car; I am dreaming. The past form here does not mean past time — it means 'not real.' 'If I were you, I would rest.' We say were for every person in this pattern: if I were, if she were. Use the second conditional for dreams, wishes, and polite advice: 'If I were you…'

Two small rules finish the picture. First, the comma: when the if part comes first, put a comma after it — 'If you are hungry, eat something.' When the result comes first, no comma — 'Eat something if you are hungry.' Second, if and when are different: use if when you are not sure ('If he comes…' = maybe), and when when you are sure ('When he comes…' = he is definitely coming). Also meet unless: unless means 'if… not.' 'Unless you hurry, you'll be late' = 'If you don't hurry, you'll be late.'

3. Formula / structure

Step by step — how to build a sentence:

comma rule:

first conditional (real future):

second conditional (imagined):

unless:

zero conditional (facts):

4. When to use it

• Zero — science and facts: 'If you mix red and blue, you get purple.'
• Zero — habits and routines: 'If I wake up early, I go for a run.'
• Zero — instructions and warnings: 'If the machine is hot, don't touch it.'
• First — real future plans: 'If the weather is good, we'll have a picnic.'
• First — promises and warnings: 'If you help me, I'll pay you back on Friday.' / 'If you touch that, you'll get hurt.'
• Second — dreams and wishes: 'If I could fly, I would visit every country.'
• Second — advice: 'If I were you, I would see a doctor.'
• Second — imaginary questions: 'What would you do if you lost your job?'

5. When NOT to use it

• Don't put will in the if part: ✗ 'If it will rain, we'll stay' → ✓ 'If it rains, we'll stay.' Will belongs in the result.
• Don't put would in the if part: ✗ 'If I would have time, I would help' → ✓ 'If I had time, I would help.'
• Don't use the second conditional for a real forecast: ✗ 'If it rained tomorrow, we would stay home' → ✓ 'If it rains tomorrow, we will stay home.'
• Don't use if when you are sure — use when: for a known schedule, ✓ 'When the movie ends at nine, we'll eat after.'
• Don't add 'not' after unless — unless already means 'if not': ✗ 'Unless you don't study, you'll fail' → ✓ 'Unless you study, you'll fail.'

6. Positive examples

• If you heat water to 100 degrees, it boils.
• If I don't set an alarm, I oversleep.
• If it snows tomorrow, the kids will build a snowman.
• If you finish early, you can leave.
• If she calls, I'll tell her the news.
• If I had more money, I would buy a bigger house.
• If we lived near the sea, we would swim every day.
• What would you do if you found a wallet on the street?
• If I were you, I would apologize.
• Unless the traffic is bad, we'll arrive by six.
• If he doesn't apologize, she won't forgive him.
• If I could speak Japanese, I would move to Tokyo.

7. Negative examples

• If you don't water the plants, they die.
• If it doesn't rain on Saturday, we won't cancel the game.
• If I weren't so busy, I would help you.
• We won't go out if it's too cold.
• If she didn't like dogs, she wouldn't have three.
• Unless you have a ticket, you can't enter.

8. Questions

• What will you do if the car breaks down?
• If you won a free trip, where would you go?
• Do you sleep well if you drink coffee in the evening?
• Will you call me if you arrive late?
• What would happen if nobody paid taxes?
• If the store is closed, where will we buy bread?

9. Short answers

• Will you help me if I ask? — Yes, I will. / Of course I will.
• Would you move abroad if you could? — Yes, I would. / No, I wouldn't.
• Do you get tired if you work late? — Yes, I do.
• If it rains, will the game stop? — Yes, it will.
• Would he come if we invited him? — Yes, he would.

10. Common mistakes

11. American English notes

12. Similar grammar — comparison

13. Natural spoken English

• 'If you're late again, the boss is gonna be mad.'
• 'I'd love to help, but if I leave now, I'll miss my train.'
• 'If I were you, I'd grab that deal before it's gone.'
• 'We'll order pizza if nobody wants to cook.'
• 'If it rains, we're staying in tonight.'
• 'What would you do if you were me?'

14. Real-life examples

• Weather news: 'If the storm hits tonight, schools will close tomorrow.'
• At work: 'If the client agrees, we'll start the project on Monday.'
• Travel: 'If your flight is delayed, the airline will give you a hotel room.'
• Shopping promises: 'If it doesn't fit, you can return it within 30 days.'
• Family advice: 'If I were you, I'd save that money for emergencies.'
• Health: 'If the pain gets worse, see a doctor.'

15. Mini dialogue

16. Summary

17. Practice exercises

Warm up with the first questions, then take the full quiz — every answer has a detailed explanation (parts 19–20 of this lesson: answer key + explanations live inside the quiz feedback).

18. The full quiz

50 questions, mixed formats, in difficulty order: easy → medium → intermediate → challenging → advanced.

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