Hi there!
This post is dedicated to conditional subordinate clauses. There are several structures in English that are called conditionals. "Condition" means situation or circumstance. If a particular condition is true, then a particular result happens.
There are four basic conditionals that we use very often, namely zero, first, second and third conditionals, thus I will refer to the four of them in this post. As usual, we will finish with some quizzes to check your understanding.
Structure of conditional sentences
The structure of most conditionals is very simple. There are two basic possibilities. Of course, we add many words and can use various tenses, but the basic structure is usually like this: [If condition], [result]; or like this: [result] [if condition].
Zero Conditional: True condition
When we talk about things that are generally or always true, we can use the connectors if, when or unless plus a present in the subordinate clause, and a present simple or imperative in the main clause:
[If/When/Unless +present], [present/imperative]
If he gets there before me, ask him to wait.
When you fly budget airline, you have to pay for your drinks and snacks.
Unless you need more space, a small car is big enough for one person.
Note that we are not talking about a specific event but something which is generally true. In the condition clause, we can use a variety of present forms (simple, continuous or even perfect). In the result clause, there can only be the present simple or imperative.
If you visit London, go on the London Eye.
If unemployment is rising, people tend to stay in their present jobs.
If you've done that, go and have a coffee.
When you go on holiday, take plenty of sun cream. It'll be very hot.
When I'm concentrating, please don't make so much noise.
When I've finished an article, I always ask Kate to read it through.
Notice that unless means the same as if not.
Unless he asks you politely, refuse to do any more work on the project.
Unless prices are rising, it's not a good investment.
First Conditional: Possible condition
We use the First Conditional to talk about future events that are likely to happen. That is why they are known as open or possible conditions. We use the connectors if or unless plus a present in the subordinate clause, and in the main clause a will-future. Remember that unless means the same as if not.
If we take John, he'll be really pleased.
If you give me some money, I'll pay you back tomorrow.
If they tell us they want it, we'll have to give it to them.
If Mary comes, she'll want to drive.
Unless you study harder this term, you won’t pass the subject.
The if-clause can be used with different present forms, although it is common to have a present simple.
If I go to New York again, I'll buy you a souvenir from the Empire State Building.
If he's feeling better, he'll come.
If she hasn't heard the bad news yet, I'll tell her.
The future clause can contain going to or the future perfect as well as will, and other modal verbs such as can, may and must.
If I see him, I'm going to tell him exactly how angry I am.
Unless we get the contract, we'll have wasted a lot of time and money.
If you go to New York, you must have the cheesecake in Lindy's.
If he comes, you can get a lift home with him.
Second Conditional: Impossible condition
The Second Conditional is used to talk about impossible situations. The condition is not possible to happen because the situation is hypothetical.
If we were in London today, we would be able to go to the concert in Hyde Park.
If I had millions dollars, I'd give a lot to charity.
If there were no hungry people in this world, it would be a much better place.
If everyone had clean water to drink, there would be a lot less disease.
Note that after I / he/ she /it we must use the subjunctive form were and not was. Some people think that were is the only 'correct' form but other people think was is equally 'correct.' It is a matter of accents, for the form was is widely used in American English.
If she were happy in her job, she wouldn't be looking for another one.
If I were in Japan, I'd have sushi every day.
If she were to enter our market, she'd have big problems.
Note the form ‘If I were you’ which is often used to give advice.
If I were you, I'd look for a new place to live.
If I were you, I'd go back to school and get more qualifications.
The Second Conditional is also used to talk about 'unlikely' situations.
If I went to China, I'd visit the Great Wall.
If I were the President, I'd reduce taxes.
If you were in my position, you'd understand.
Note that the if-clause can contain the past simple or the past continuous.
If I were still working in Brighton, I would commute by train.
If she were coming, she would be here by now.
If they were thinking of selling, I would want to buy.
Note that the main clause can contain would, could or might.
If I had the chance to do it again, I would do it differently.
If we met up for lunch, we could go to that new restaurant.
If I spoke to him directly, I might be able to persuade him.
Also note that sometimes the if-clause is implied rather than spoken.
What would I do without you? ("if you weren't here")
Where would I get one at this time of night? ("if I wanted one")
He wouldn't agree. ("if I asked him")
Third Conditional: Past impossible condition
We can use the Third Conditional to talk about impossible conditions, impossible because they are in the past and we cannot change what has happened.
If I had worked harder at school, I would have got better grades.
If I had had time, I would have gone to see him. But I didn't have time.
If we had bought that house, we would have had to rebuild the kitchen.
If we had caught the earlier train, we would have got there on time but we were late.
Notice that the main clause can contain would have, could have or might have.
If I had seen him at the meeting, I would have asked him. (But he wasn't there so I didn't.)
If I had seen him at the meeting, I could have asked him. ( But he wasn't there so it wasn't possible.)
If I had seen him at the meeting, I might have asked him. (But I'm not sure. Perhaps if the opportunity had arisen.)
If I had paid more attention in class, I would have understood the lesson.
Also notice that sometimes the if-clause is implied rather than spoken.
I'd have done it. ("if you had asked me but you didn't.")
I wouldn't have said that. ("if I'd been there.")
He wouldn't have let him get away with that. ("if he had tried that with me.")
Finally, observe that apart from if or unless, other conjunctions can express condition, like, for example, provided (that), providing (that), on (the) condition that, only if, as long as, in case, in the event that, otherwise, or (else) and the inversion with should.
In the event that trouble should start, lock all the doors and windows.
Provided that he didn't drive it too fast, I told him he could borrow my car.
Take an umbrella in case it rains.
You had better lock all the doors otherwise you will be in trouble.
Should you leave these rooms, you will not by any chance go to sleep in any other part of the castle.
Finally, observe that apart from if or unless, other conjunctions can express condition, like, for example, provided (that), providing (that), on (the) condition that, only if, as long as, in case, in the event that, otherwise, or (else) and the inversion with should.
In the event that trouble should start, lock all the doors and windows.
Provided that he didn't drive it too fast, I told him he could borrow my car.
Take an umbrella in case it rains.
You had better lock all the doors otherwise you will be in trouble.
Should you leave these rooms, you will not by any chance go to sleep in any other part of the castle.
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