Conditionals
Conditionals are sentences that describe what happens (or would happen) if a certain condition is met. They let you talk about facts, real possibilities, imaginary situations, and things that could have happened differently in the past.
What You'll Learn
- How to form and use all four conditional types (Type 0, 1, 2, and 3)
- When to use "were" instead of "was" in hypothetical sentences (the subjunctive)
- How to use "unless" as a replacement for "if...not"
- How to identify the correct conditional type based on meaning and context
When to Use
- Universal truths and scientific facts (Type 0): "If you heat water to 100 degrees Celsius, it boils."
- Real or likely future events (Type 1): "If it rains tomorrow, we will cancel the outdoor assembly."
- Hypothetical or imaginary present situations (Type 2): "If I were the class monitor, I would organise more group activities."
- Imaginary past situations — things that did not happen (Type 3): "If she had studied harder, she would have scored better on the exam."
- Conditions using "unless" (any type): "You will not pass unless you revise regularly." (= If you do not revise regularly, you will not pass.)
How to Form
Type 0 — Zero Conditional (Universal Truths)
Use this when the result always happens whenever the condition is true.
| If-Clause | Main Clause | Example |
|---|---|---|
| If + present tense | present tense | If you mix red and blue, you get purple. |
| If + present tense | present tense | If ice is left in the sun, it melts. |
Type 1 — First Conditional (Real Future)
Use this when the condition is possible or likely to happen.
| If-Clause | Main Clause | Example |
|---|---|---|
| If + present tense | will + base verb | If we finish early, we will go to the hawker centre. |
| If + present tense | will + base verb | If he practises every day, he will improve his spelling. |
Type 2 — Second Conditional (Hypothetical Present/Future)
Use this for situations that are imaginary, unlikely, or contrary to reality right now.
| If-Clause | Main Clause | Example |
|---|---|---|
| If + past tense | would + base verb | If I had a million dollars, I would donate half to charity. |
| If + were | would + base verb | If she were taller, she would join the basketball team. |
Important: In Type 2 conditionals, always use "were" for all subjects, not "was". This is the subjunctive mood.
- "If I were you..." (Not:
If I was you...)- "If he were here..." (Not:
If he was here...)
Type 3 — Third Conditional (Past Unreal)
Use this for situations that did not happen in the past. You are imagining a different outcome.
| If-Clause | Main Clause | Example |
|---|---|---|
| If + past perfect (had + past participle) | would have + past participle | If I had woken up earlier, I would have caught the bus. |
| If + past perfect | would have + past participle | If they had checked the weather forecast, they would have brought umbrellas. |
Using "Unless"
"Unless" means "if...not". It introduces the only condition that would prevent the result.
| Unless Sentence | Equivalent If...Not Sentence |
|---|---|
| You will be late unless you leave now. | You will be late if you do not leave now. |
| She won't forgive him unless he apologises. | She won't forgive him if he does not apologise. |
| Unless it rains, we will have the picnic outdoors. | If it does not rain, we will have the picnic outdoors. |
Key Rules
-
Type 0 uses present tense in both clauses: Both the if-clause and the main clause use the simple present because the result is always true. "If you drop a ball, it falls."
-
Type 1 uses present tense + will: The if-clause is in the present tense, and the main clause uses "will" + base verb. Never put "will" in the if-clause. "If it rains, we will stay indoors." (Not:
If it will rain...) -
Type 2 uses past tense + would: The if-clause uses the simple past (or "were" for the subjunctive), and the main clause uses "would" + base verb. "If I knew the answer, I would tell you."
-
Always use "were" (never "was") in Type 2: Regardless of the subject, the correct form is "were" in hypothetical if-clauses. "If she were the captain..." "If it were possible..."
-
Type 3 uses past perfect + would have: The if-clause uses "had" + past participle, and the main clause uses "would have" + past participle. "If he had arrived on time, he would have seen the performance."
-
"Unless" replaces "if...not" — do not add "not" after "unless": Since "unless" already means "if not", adding "not" creates a double negative. "Unless you study..." (Not:
Unless you don't study...) -
The if-clause can come first or second: When the if-clause comes first, use a comma before the main clause. When the main clause comes first, no comma is needed. "If I were you, I would apologise." / "I would apologise if I were you."
Common Mistakes
| Wrong | Right | Why |
|---|---|---|
| If it will rain, we will stay home. | If it rains, we will stay home. | Never use "will" in the if-clause of a Type 1 conditional |
| If I was the principal, I would change the rules. | If I were the principal, I would change the rules. | Type 2 requires "were" (subjunctive), not "was" |
| If she had studied, she would pass. | If she had studied, she would have passed. | Type 3 requires "would have + past participle" in the main clause |
| Unless you don't hurry, you will be late. | Unless you hurry, you will be late. | "Unless" already means "if not"; adding "not" creates a double negative |
| If I have a car, I would drive to school. | If I had a car, I would drive to school. | Type 2 requires past tense in the if-clause, not present tense |
| If he had knew the answer, he would have told us. | If he had known the answer, he would have told us. | After "had", use the past participle ("known"), not the past tense ("knew") |
Clue Words
Type 0 clue words (facts and general truths)
always, every time, whenever, generally, as a rule
Type 1 clue words (real future possibility)
tomorrow, next week, soon, if...will, probably
Type 2 clue words (hypothetical/imaginary now)
were, would, imagine, suppose, what if, hypothetically
Type 3 clue words (imaginary past)
had + past participle, would have, could have, might have, if only
"Unless" clue
unless = if...not
Tip: Look at the verb tenses to identify the conditional type. Present + present = Type 0. Present + will = Type 1. Past/were + would = Type 2. Past perfect + would have = Type 3. If you see "unless", mentally replace it with "if...not" to check whether the sentence makes sense.
Practice Tips
-
Tense-matching check: After writing a conditional sentence, verify that the tenses in both clauses match the correct type. Draw a line connecting the if-clause to the main clause and check: Does "present + will" (Type 1) or "past + would" (Type 2) or "past perfect + would have" (Type 3) hold true?
-
The "were" habit: Whenever you write a Type 2 conditional, automatically use "were" for every subject. Train yourself to write "If I were...", "If he were...", "If it were..." without thinking twice.
-
Unless substitution test: Replace "unless" with "if...not" and re-read the sentence. If the meaning stays the same, your sentence is correct. If you end up with a double negative ("if...not...not"), you have made an error.
-
Reality check: Before choosing a conditional type, ask yourself three questions. Is this always true? (Type 0.) Is this possible in the future? (Type 1.) Is this imaginary right now? (Type 2.) Did this not happen in the past? (Type 3.) Your answer determines the type.
Quick Reference
| Type | Name | If-Clause | Main Clause | Example |
|---|---|---|---|---|
| 0 | Zero (universal truth) | If + present tense | present tense | If you heat ice, it melts. |
| 1 | First (real future) | If + present tense | will + base verb | If she calls, I will answer. |
| 2 | Second (hypothetical) | If + past tense / were | would + base verb | If I were you, I would study harder. |
| 3 | Third (past unreal) | If + past perfect | would have + past participle | If I had known, I would have helped. |
| -- | Unless (= if...not) | Unless + positive verb | (matches the type) | Unless you hurry, you will be late. |