Conditional sentences typically contain two clauses – the conditional clause (or if clause) and the main clause (or result clause). They allow us to talk about possible and impossible/unreal situations and their consequences.
When the if-clause comes before the result clause, we usually separate the two clauses with a comma. When the result clause comes first, we do not use a comma.
e.g. If you share a car to work, you can save on energy. = You can save on energy if you share a car to work.
I. Types of Conditional Sentences
a. Zero Conditional
Form: If/When/Whenever + present simple, present simple
+ To talk about general or scientific facts and definitions
E.g. If you mix oil and water, the oil floats.
+ To talk about a straightforward cause and effect
E.g. If they’re short of money, they don’t eat out.
b. First Conditional
Form: If + a present tense, will + bare infinitive
Usage: To talk about very possible or probable situations/events in the present or future
- If we hurry, we’ll catch the bus.
- If you’re working till half past six, we’ll have dinner at about eight.
- If you’ve finished with the computer, I’ll put it away.
– We can also use a form of the first conditional to give instructions about real or likely situations in the present or future. This is: if + a present tense, imperative.
e.g. If the people from Greenpeace call, tell them I’ll call them back later.
If anyone should call, please take a message.
– We can also use may, might, can, could, shall, should, ought to, have to instead of will, depending on the meaning.
e.g. If Matthew is going to a job interview, he should wear a tie.
If you haven’t got a television, you can’t watch it, can you?
– We can also use should + bare infinitive instead of the present simple. This suggests the situation is possible, but unlikely to happen.
e.g. If you should bump into him, you’ll be able to get a lift home.
c. Second Conditional
Form: If + past simple/past continuous, would + bare infinitive
Usage: To talk about improbable or imaginary situations/events in the present or future
- If he were here right now, he would help us.
- What would the local government do if there was an earthquake in the area?
- If I was/were you, I would think more carefully about my future.
– We can also use might or could instead of would, depending on the meaning. (Note: could here often means would be able to.)
e.g. If we were older, we could go on holiday on our own.
– We can also use could in the if clause. Here, it means was/were able to.
e.g. If I could drive, I’d buy a car.
– In British English, we can use both was and were after if with first and third-person singular. Were is more common in a formal style. In American English, it is usual to use were.
UK: If I was/were a gambler, I’d put money on Jim being late.
US: If I were a gambler, I’d put money on Jim being late.
– In both British and American English, were is usually used in the phrase If I were you, … .
d. Third Conditional
Form: If + past perfect (simple or continous), would + have + past participle
Usage: To talk about imaginary or “unreal” situations in the past.
- If you had worn a fake beard, no one would have known who you were! (You didn’t wear a fake beard, so people knew who you were.)
- If it hadn’t been snowing, we wouldn’t have got lost. (It was snowing, so we got lost)
– We can also use might, could, or should instead of would, depending on the meaning.
e.g. If I had done some revision, I might/could/should have passed the exam.
– With second and third conditionals in informal conversation, speakers of American English sometimes use would or would have in the if-clause. This is very unusual in British English.
US: How would you feel if this happened / would happen to you?
UK: How would you feel if this happened to you?
US: I would have felt awful if that had happened / would have happened to me.
UK: I would have felt awful if that had happened to me.
e. Mixed Conditional
- If + past perfect (simple or continuous), would + bare infinitive (1)
- If + past simple/past continuous, would + have + past participle (2)
(1) is used to talk about present results of an imagined past condition/action.
E.g. If I had listened to my parents, I wouldn’t be in so much trouble now. (= I didn’t listen to my parents, so I’m in lots of trouble now.)
(2) is used to talk about imagined past results of a present condition/situation.
E.g. If I had a mobile, I would have called you last night. (= I don’t have a mobile, so I didn’t call you last night.)
Watch out: In conditional sentences, modals (will, would, could, etc.) are sometimes followed by a continuous infinitive.
e.g. We’d still be waiting if you hadn’t turned up.
II. Other Uses of Conditional Sentences
- If I were you, I would + bare infinitive is used to give advice
E.g. If I were you, I’d take that laptop as hand luggage. = You should/had better take that laptop as hand luggage.
- If you would + bare infinitive, …. would + bare infinitive is used to make criticisms or strong requests
E.g. If you’d stop making so much noise, perhaps we’d all be able to enjoy the programme.
- I’d appreciate it / I’d be grateful if you would/could …. is used to make polite formal requests
E.g. I’d appreciate it if you could hand in the report by Sunday.
III. Inverted Conditional Sentences
Three types of If-sentences can be inverted without If-. This makes the sentences more formal and makes the event less likely. In this type of inversion, we should not use contractions.
a. Conditional sentences type I
The formation of this conditional is by omitting “if” and by putting “should” at the beginning of the clause. The rest of the clause will be the same.
E.g. If you should arrive at the airport before 12:00, give me a call. => Should you arrive at the airport before 12:00, give me a call.
If she should call, I will invite her. => Should she call, I will invite her.
b. Conditional sentences type II
There are two ways of forming conditional sentences in this type.
• If the if-clause consists of “were”, just invert between the subject and were.
• If the if-clause consists of “action verb”, the verb must be restructured into: were … to V
E.g. If he were rich, he would have an expensive car. => Were he rich, he would have an expensive car.
If I had the money, I would buy you what you want. => Were I to have the money, I would buy you what you want.
c. Conditional sentences type III
Conditional without “if” in this type is constructed by omitting “if” and foregrounding the auxiliary verb “had”. We can also use conditional structures beginning with were … to have Vpp in formal English.
E.g. If I had known, I would have protested strongly. => Had I known, I would have protested strongly.
If the police had found out, I would have been in trouble. => Were the police to have found out, I would have been in trouble.
Watch out: When the verb to be inverted is negative, we put not after the subject.
e.g. Had we not attended the meeting, we would have had no idea of the council’s plans.
IV. Other Conditional Structures
- Unless = except if; if…not
E.g. Unless governments act now, the environment is really going to suffer.
- Otherwise is used to state what the result would be if something did not happen or if the situation were different
E.g. My parents lent me the money. Otherwise, I couldn’t have afforded the trip.
- So/As long as = if; only if
E.g. As/So long as I’m happy, my parents don’t care what job I do.
- Provided/Providing (that) = On (the) condition (that) = if; only if
E.g. You can have a pet provided that you promise to look after it properly.
Applications for membership are accepted on condition that applicants are over 18.
- Suppose/Supposing/Imagine is used to ask about imaginary situations
E.g. Imagine you had a million dollars, what would you spend it on?
Supposed they lived in the country, would they feel safe?
- (just) in case (…) means “because of the possibility of something happening”
E.g. Take a coat with you in case the weather gets worse.
- In case of + noun = if something happens
E.g. In case of fire, leave the building by the nearest emergency exit.
- If not is used to introduce a different suggestion, after a sentence with if
E.g. I’ll go if you’re going. If not (= if you are not), I’d rather stay at home.
- If so = if that is the case
E.g. Are you concerned about the environment? If so, you might be interested in joining Greenpeace.
- Even if = despite the possibility that; no matter whether
E.g. I’ll get there, even if I have to walk.
- If it wasn’t/weren’t for + noun; or Were it not for + noun is used to say who or what prevents or prevented something from happening
E.g. I think I’d be quite lonely if it wasn’t/weren’t for my dog, Buster. = Were it not for my dog, Buster, I think I’d be quite lonely.
- If it hadn’t been for + noun; or Had it not been for + noun is used to say who or what prevents or prevented something from happening
E.g. If it hadn’t been for your help, I wouldn’t have been able to quit gambling. = Had it not been for your help, I wouldn’t have been able to quit gambling.
- But for/without + noun means that “something would have happened if something else or someone had not prevented it”
E.g. But for/without your help, I wouldn’t have been able to quit gambling. (= If you hadn’t helped me, I wouldn’t have been able to quit gambling.)
V. Sentences with “Wish” and “If only“
- I wish/If only + past simple is used to express a desire for something to be different in the present
E.g. I wish (that) Mark knew about it.
If only Mark knew about it! (Sadly, Mark doesn’t know about it.)
- I wish/If only + would is used to express a future wish – something we would like to happen
E.g. If only Mark would come back! (I’m afraid he won’t.)
I wish you’d stop doing that. (You’re annoying me.)
- I wish/If only + past perfect is used to express a wish that something different had happened in the past
E.g. I wish someone had told my mother about it.
– We use a past tense or could instead of would with wish when the subject pronouns are the same:
e.g. I wish I could be more energetic. (NOT:
I would be more energetic.)
If only I was more energetic.
– Wish + would can be used when the speaker wants an action or event to change. We often use it to criticise or complain about something. Note that it cannot be used for situations.
e.g. It is raining. I wish it would stop.
I wish you would know the answer.
If only you wouldn’t shout. It’s really irritating.
– Were is often used instead of was after wish and If only:
e.g. I wish Luke were here.
– Wishes about the future can be expressed with were going to, could, or would. The speaker wants the situation to be the opposite of what it will be.
e.g. I wish he were going to be here next week.
I wish she could come tomorrow.
– We can use could + have + past participle for a regret about the past.
e.g. I wish my friend could have been there. (Unfortunately, he wasn’t able to be there.)
– If only is often more emphatic than I wish.
e.g. If only we’d seen you coming. We might have braked in time. (a regret)
I wish we’d seen you coming. We would have put out the red carpet! (a wish)
– For greater emphasis, we can put the subject between if and only in informal English.
e.g. If you only knew how much trouble you’ve caused!.
– To express a preference rather than a wish, we use would rather/sooner.
e.g. Do you mean you’d sooner I weren’t/wasn’t here?
I’d rather you hadn’t spoken so rudely to him.