I
Real or Possible Condition
Use this type when the condition can really happen in the present or future.
If + Simple Present, will / can / may / must + V1
RULE 04
Conditional Sentences
Conditional sentences describe a result that depends on a condition. They are usually formed with an if-clause and a main clause.
Three Main Types
II
Imaginary or Unlikely Condition
Use this type for a condition that is possible in theory, but unlikely or imaginary.
If + Simple Past, would / could / might + V1
III
Impossible Past Condition
Use this type when the condition belongs to the past and can no longer be changed.
If + Past Perfect, would / could / might + have + V3
Structure Table
| Type | Condition | If-Clause | Main Clause |
|---|---|---|---|
| Type I | Possible to fulfill | Simple Present | will / shall / can / may / must + V1 |
| Type II | Possible in theory | Simple Past | would / could / might / should + V1 |
| Type III | Too late to fulfill | Past Perfect | would / could / might / should + have + V3 |
Examples by Type
Type I
If I study regularly, I will pass the exam.
Type I
If your files are in order, you may leave at once.
Type I
If you want to lose weight, you must eat less fatty food.
Type I
If it rains tomorrow, we will cancel the picnic.
Type II
If I studied harder, I would pass the exam.
Type II
If I lived near the metro station, I would reach work on time.
Type II
If I were you, I would plant saplings around the house.
Type II
If she had more free time, she could learn French.
Type III
If I had studied, I would have passed the exam.
Type III
If we had found him earlier, we could have arrested him and prevented the crime.
Type III
Had you obeyed orders, this fire accident would have been averted.
Type III
If they had left earlier, they might have caught the train.
Important Note: Universal Truth
These rules change when the sentence expresses a universal truth or scientific fact. In such cases, we often use the simple present in both clauses.
Example: If water reaches 100°C, it boils.
Example: If you heat water, it turns into vapour.
Example: If the sun sets, darkness follows.
