Sentences with 'if': A conditional sentence talks about a condition and its result: "If something happens, then something else happens." It has two halves — the if-clause (the condition) and the main clause (the result).
English has four conditionals. The one you choose depends on how real or likely the situation is — from a general truth, to a real future, to an imaginary present, to an impossible past.
- conditional
- a sentence that links a condition to its result, usually using 'if'
- if-clause
- the half that gives the condition ("If it rains…")
- main clause / result clause
- the half that gives the result ("…we'll stay in")
- zero conditional
- for general truths and facts (if + present, present)
- first conditional
- for a real, likely future situation (if + present, will + base verb)
- second conditional
- for an unreal or unlikely present/future (if + past, would + base verb)
- third conditional
- for an unreal, impossible past (if + past perfect, would have + past participle)
- unless
- a way to say 'if not' ("Unless you hurry, you'll be late")
Why it carries the marks: Conditionals show off a range of tenses and structures — exactly what Criterion A (Language) rewards. A confident "If I were you, I would…" or "If I had known, I would have…" lifts a written answer or oral above the safe present-tense level. Examiners notice the wrong form ("If I will…") immediately, so the patterns are worth learning precisely.
Four patterns, one logic: Each conditional pairs a tense in the if-clause with a structure in the main clause. The key idea: the less real the situation, the further back the tense moves.
Golden rule: never put will or would in the if-clause. Write "If it rains…" (not "If it will rain…") and "If I had time…" (not "If I would have time…").
| Type | If-clause | Main clause | Example |
|---|---|---|---|
| Zero | present simple | present simple | If you heat ice, it melts. |
| First | present simple | will + base verb | If it rains, we will stay in. |
| Second | past simple | would + base verb | If I won the lottery, I would travel. |
| Third | past perfect | would have + past participle | If I had left earlier, I would have caught the bus. |
Two handy details: 1. 'were' for everyone (2nd conditional). In careful English we use were for all subjects: "If I were you, I would apologise." ("If I was…" is common in speech but "were" is the exam-safe form.)
2. Contractions. The result clause is usually contracted: "we 'll stay" (first), "I 'd travel" (second), "I 'd have caught" (third). Both the full and contracted forms are correct.
Stop wasting time on topics you know
Our AI identifies your weak areas and focuses your study time where it matters. No more overstudying easy topics.
Try Smart Study Free7-day free trial • No card required
How real is the idea?: Choosing the right conditional is really one question: how real is the situation? A fact you can always rely on → zero. Something that may genuinely happen → first. Something imaginary or unlikely now → second. Something that did not happen in the past → third.
Which one to use
- Zero — a general truth or rule: "If you don't water plants, they die."
- First — a real future possibility: "If I finish my homework, I'll watch a film."
- Second — an imaginary/unlikely present + advice with 'If I were you…': "If I were you, I'd take the earlier train."
- Third — regret or a different past: "If we had booked earlier, the flight would have been cheaper."
- Unless = 'if not': "You'll miss the bus unless you leave now."
Real / possible
- Zero — always true: "If you press this, the light comes on."
- First — could really happen: "If she calls, I'll answer."
Unreal / imaginary
- Second — not the case now: "If I lived by the sea, I'd swim every day."
- Third — didn't happen: "If you had told me, I would have helped."
Comma rule (word order): Either clause can come first. When the if-clause comes first, put a comma between the clauses: "If it rains, we'll stay in." When the main clause comes first, you need no comma: "We'll stay in if it rains." The meaning is the same.
All four, one after another: Here are the four conditionals built up step by step around a single idea. Watch how the tense moves further back as the situation becomes less real, while the result clause climbs from get/comes → will → would → would have.
IB-style task — the four conditionals in action
From general truth to impossible past
- Zero conditional (a general truth): "If you mix blue and yellow, you get green." — both verbs are in the present, because this is always true.
- First conditional (a real future possibility): "If it rains tomorrow, we'll cancel the trip." — if + present, then will + base verb.
- Second conditional (an unreal or unlikely present): "If I had more time, I would learn the piano." — if + past, then would + base verb.
- Third conditional (an unreal past): "If I had studied harder, I would have passed the exam." — if + past perfect, then would have + past participle.
- Notice the pattern: the further from reality the idea is, the further 'back' the tense moves — present → past → past perfect — while the result clause climbs will → would → would have.
Steal this for your writing: You don't need all four in every answer — but slipping in one well-formed second or third conditional ("If I were…, I would…" / "If I had known…, I would have…") signals a strong command of structure. Plan one in advance for your oral or a Paper 1 task.
See how examiners mark answers
Access past paper questions with model answers. Learn exactly what earns marks and what doesn't.
Try Exam Vault Free7-day free trial • No card required
The slips to watch for: Three mistakes dominate. 1. Putting will/would in the if-clause ("If it will rain…"). 2. Mixing up the two halves of a conditional ("If I had time, I will help" — should be would). 3. Forgetting the comma when the if-clause comes first. Compare the right version with the typical mistake and the fix becomes obvious.
Correct
- If it rains, we'll stay in.
- If I had more money, I would travel.
- If I had known, I would have called you.
Common mistake
- If it will rain, we'll stay in. (no 'will' in the if-clause → if it rains)
- If I would have more money, I would travel. (no 'would' in the if-clause → if I had)
- If I had known, I would called you. (third needs 'would HAVE called')
Ask: how real, and is each half correct?: Before you write a conditional, do two quick checks. 1. Decide how real the idea is (fact → first → second → third) so you pick the right type. 2. Make sure the two halves match the pattern — and keep will/would out of the if-clause. If the if-clause comes first, add the comma.