When we are thinking about a situation in the present or future that is hypothetical, unlikely or impossible, we use:
If + Past Simple, …Would + Verb
We use a past verb though are imagining the present or the future to be different.
The second clause of subject + would + verb (conditional verb) is conditional to the first clause happening (or will only happen if the first part/clause happens).
Example: If I won the lottery, I would travel around the world.
= It is unlikely that I will win the lottery, but I’m going to hypothetically imagine that I did win. In that situation I would travel around the world. So in order for me to travel around the world, I would need the first clause (the condition or situation) to happen, that is, for me to win the lottery first.
- If I won the lottery, I would travel around the world. (Though I am unlikely to win the lottery)
- If I knew his name, I would tell you.
- If I didn’t have a headache, I would go to the party.
- If I became President, I would reduce the salaries of all politicians. (Though it is unlikely I will become President)
Notice how we use a comma after the past tense clause.
We can also reverse the order and use:
Conditional verb (would + verb) + If + Past Simple
- I would be happy if I had more free time.
- I would tell you the answer if I knew what it was.
- There would be fewer accidents if everyone drove more carefully.
- We would have a lot of money if we sold our house.
- Would she come if I paid for her flight?
- Would you accept the job if they offered it to you?
- What would you do if you won the lottery?
- What would you do if you saw a U.F.O?
If I were …
Note that with the verb To Be we use IF + I / HE / SHE / IT + WERE
The reason we use WERE instead of WAS is because the sentence is in the Subjunctive mood.
If I were not in debt, I would quit my job.
If he were taller, he’d be accepted into the team.
She would be still be correcting my grammar if she were still alive.
Though in informal English, you will hear some people say If I was… If he was… etc. This usage doesn’t sound good though unfortunately is common.
When we are talking about something in the past which cannot be altered now, we use:
If + Past Perfect, would have + past participle
EXAMPLE: If you had studied all of these grammar pages, you would have passed the exam.
You can not alter or change the past. You didn’t study in the past (something you cannot change now) so you didn’t pass the exam. It is an imaginary situation that didn’t happen.
- If you had been more careful, you wouldn’t have had an accident.
- If I had seen you, I would have said hello.
- If he had asked me, I would have helped him.
- If you had studied, they would have passed the exam.
- If I had known, I wouldn’t have done that.
Notice how this tense can be used to say that you regret doing something or when you are telling someone off (reproaching someone). This type of conditional can also be used when making excuses.
We can also change the word order of the sentence…
Would have + If + past perfect
EXAMPLE: You would have passed the exam if you had studied all of these grammar pages.
- I wouldn’t have left my job if I had known how difficult it is to find another one.
- I would have taken a photo if I had brought my camera with me.
- He would have died if the ambulance hadn’t arrived quickly.
- She would have gone to your birthday party if she hadn’t been sick.
- He wouldn’t have become lost if he had taken the map with him.
- The team would have won if the referee hadn’t taken the bribe.
- You wouldn’t haved needed fillings if you had brushed your teeth more frequently.