Conditional sentences are sometimes confusing for learners of English as a second language.
- Which type of conditional sentences is it?
- Where is the if-clause (e.g. at the beginning or at the end of the conditional sentence)?
There are three types of conditional sentences.
|I||condition possible to fulfill|
|II||condition in theory possible to fulfill|
|III||condition not possible to fulfill (too late)|
|I||Simple Present||will-future or (Modal + infinitive)|
|II||Simple Past||would + infinitive *|
|III||Past Perfect||would + have + past participle *|
2. Examples (if-clause at the beginning)
|type||if clause||main clause|
|I||If I study,||I will pass the exam.|
|II||If I studied,||I would pass the exam.|
|III||If I had studied,||I would have passed the exam.|
3. Examples (if-clause at the end)
|I||I will pass the exam||if I study.|
|II||I would pass the exam||if I studied.|
|III||I would have passed the exam||if I had studied.|
4. Examples (affirmative and negative sentences)
|long forms||short/contracted forms|
|I||+||If I study, I will pass the exam.||If I study, I‘ll pass the exam.|
|–||If I study, I will not fail the exam.
If I do not study, I will fail the exam.
|If I study, I won’t fail the exam.
If I don’t study, I‘ll fail the exam.
|II||+||If I studied, I would pass the exam.||If I studied, I‘d pass the exam.|
|–||If I studied, I would not fail the exam.
If I did not study, I would fail the exam.
|If I studied, I wouldn’t fail the exam.
If I didn’t study, I‘d fail the exam.
|III||+||If I had studied, I would have passed the exam.||If I‘d studied, I‘d have passed the exam.|
|–||If I had studied, I would not have failed the exam.
If I had not studied, I would have failed the exam.
|If I‘d studied, I wouldn’t have failed the exam.
If I hadn’t studied, I‘d have failed the exam.
* We can substitute could or might for would (should, may or must are sometimes possible, too).
- I would pass the exam.
- I could pass the exam.
- I might pass the exam.
- I may pass the exam.
- I should pass the exam.
- I must pass the exam.
How conditional sentences are mixed
Unreal conditionals (type II + III) sometimes can be mixed, that is, the time of the if clause is different from the one of the main clause.
1. Past → Present
- If I had taken an aspirin, I wouldn’t have a headache now.
2. Past → Future
- If I had known that you are going to come by tomorrow, I would be in then.
3. Present → Past
- If she had enough money, she could have done this trip to Hawaii.
4. Present → Future
- If I were you, I would be spending my vacation in Seattle.
5. Future → Past
- If I weren’t flying to Detroit, I would have planned a trip to Vancouver.
6. Future → Present
- If I were taking this exam next week, I would be high-strung.