Conditional sentences express that one thing depends on another. They usually contain an if-clause (condition) and a main clause (result). At the intermediate level, there are three main types.
Zero Conditional — General Truths
Form: If + present simple, present simple
Used for facts and things that are always true.
| If-clause (condition) | Main clause (result) | | --------------------- | ----------------------- | | If you heat ice | it melts. | | If it rains | the grass gets wet. | | If I am tired | I sleep badly. |
If you heat ice, it melts.
First Conditional — Real Future Possibilities
Form: If + present simple, will + base verb
Used for possible situations in the present or future.
| If-clause (condition) | Main clause (result) | | --------------------- | --------------------------- | | If it rains | I will stay home. | | If she studies | she will pass the exam. | | If you hurry | you will catch the bus. |
If it rains, I will stay home.
Second Conditional — Unreal / Hypothetical Present
Form: If + past simple, would + base verb
Used for imaginary situations that are unlikely or impossible now.
| If-clause (condition) | Main clause (result) | | ------------------------ | ------------------------------ | | If I won the lottery | I would travel the world. | | If she were taller | she would play basketball. | | If I had a car | I would drive to work. |
If I won the lottery, I would travel the world.
Note: Use were (not was) for all subjects in second conditional: If I were you...
Comparison Table
| Conditional | If-clause Tense | Main Clause | Probability | Example | | ----------- | --------------- | -------------- | --------------- | ------------------------------------- | | Zero | present simple | present simple | 100% (fact) | If you boil water, it evaporates. | | First | present simple | will + base | ~50% (real) | If you study, you will pass. | | Second | past simple | would + base | ~0% (imaginary) | If I had wings, I would fly. |
Common Mistakes
- Using will in the if-clause: ~~If it will rain, I stay.~~ → If it rains, I will stay.
- Using would in the if-clause of second conditional: ~~If I would have money, I would buy it.~~ → If I had money, I would buy it.
- Mixing zero and first conditional structures incorrectly.