Conditional sentences express a condition and its result. English has four primary conditional structures, each corresponding to different levels of reality and time frames.
Summary Formula Table
| Type | If-Clause | Main Clause | Usage |
|---|---|---|---|
| Zero | Present Simple | Present Simple | Scientific facts, universal truths |
| First | Present Simple | Will + Base Verb | Real future possibilities |
| Second | Past Simple (were) | Would + Base Verb | Hypothetical present/future |
| Third | Past Perfect (had + V3) | Would have + V3 | Unreal past regret |
The Classic Third Conditional Exam Trap
Examiners often insert "would have" in both clauses. Remember: NEVER put "would have" inside the if clause!
Incorrect: If he would have studied, he would have passed.
Correct: If he had studied, he would have passed.