- If/unless/when + present simple(or will) + present simple with general truths.
Ex: if you heat liquid to 120ªC, it boils
- If/when + present simple + will/might/may: Condition referring to a present or future event that is likely to happen.
Ex: He might be prepared to work when he finish with his studies.
- If/unless + past simple + would/could/might: Hypothetical condition (in the present or in the future).
Ex: If Marta went to school, she could speak languages.
- If/unless + past perfect + would/could/might: Hypothetical condition (in the past).
Ex: Even if I had got the job, I probably wouldn't have enjoyed it much.
In the FORMAL STYLE if can be omitted:
Ex: If I had been accepted.... without the if: Had I been accepted in college, I would have studied longer.
Supposing/ Imagine can be used instead of it.
If + was/were to : Make a situation or event seem more hypothetical.
Ex: If they were to find a way of removing ebola, millions of live would be saved.
In case is not equal to if: In case is used to talk about precautions (something done to avoid a problem).
If+should/happen to: is used to suggest that something is unlikely to happen, or may just happen by chance.
Ex: If you happen to pass a pharmacy, could you get me some aspirin?