Learning English

Conditionals review

Meaning and use

Conditional sentences express a connection between two actions or states. One thing happens because of another. These connections can be general, specific, likely, unlikely, real or imagined.

Although there are quite a few different ways of forming conditional sentences there are common patterns known as zero, first, second and third conditionals.

Zero conditionals
Used to refer to general truths, scientific facts and the predictable results of particular actions. One thing happens and because of this something else happens. In zero conditionals if and when have the same meaning. 

If you heat water enough, it boils.

When he scores, he celebrates by making a heart shape with his hands.

When it’s raining, he stays indoors.

First conditionals 
Used when we want to talk about something that is likely to happen in the future after a specific set of circumstances, the condition. If is used is when the condition is possible and when is used when the condition is certain to happen.

If I go to the shops, I’ll get some bread. (I might not go to the shops)

When I go to the shops, I’ll get some bread. (I’m definitely going to the shops)

If you’ve finished your homework by six, you can go out and play.

When you’re having your party, please keep the noise down!

Second conditionals 
Refer to an imagined present result of an unlikely or impossible present condition.

If I had the money, I’d travel around the world. (I don’t have the money)

If I were you, I’d think about leaving him. (I’m not you)

Third conditionals
Refer to an imagined past result of something that didn’t happen in the past. 

If I had known you were coming, I wouldn’t have prepared the cheese dish.
(I didn’t know you were coming. I prepared a cheese dish.)

If I had known then what I know now, I wouldn’t have wasted so much time at university.
(I didn’t know then what I know now. I did waste a lot of time at university.)

Form

Conditional sentences usually have two parts. There is the if clause (sometimes called the conditional clause) and the result clause (sometimes  called the main clause). The clauses can come in any order. 

If the if clause is first, the two clauses are separated by a comma.

There is no comma if the result clause is first.

Zero conditional

If clause:
if/when + present simple

Result clause: 
present simple

When I turn it on, it makes a funny noise.

If you multiply ten by twelve, what do you get?

Milk goes bad if you leave it out too long.

First conditional

If clause: 
if/when + present simple

Result clause: 
will / 'll + infinitive without to / imperative

If it rains, you’ll get wet.

If it rains, put your coat on.

If you’re leading at half time, I’ll let your dad know.

If you’ve won, give me a call as soon as possible.

Second conditional

If clause: 
if + past simple (exception: verb 'to be' takes 'were' in 1st and 2nd person)

Result clause: 
would / 'd + infinitive without to

If I knew what was wrong, I’d fix it myself.

I’d be out on my bike if it weren’t raining so hard.

Third conditional

If clause:
if + past perfect

Main clause: 
would / 'd + have / 've + past participle

If I'd known it'd break, I wouldn't have tried to pick it up.

If you hadn't insisted on changing your shirt we wouldn't've missed the bus.

Take note: modals

Most first, second and third conditional clauses commonly use will or would but it is possible to use other modal auxiliaries instead. For example:

First conditional

If you go to the shops, can you get some bread, please?

If you go to the shops, could you get some bread, please?

If I go to the beach at the weekend, I might try out my new wet suit.

If I get a phone call this afternoon, it may be good news.

When we go on holiday this year, we should book a nicer hotel.

Second conditional

If I had enough money, I could travel around the world.

If I were elected, I might be able to do some good.

Third conditional

If you’d told me earlier, I could’ve done something about it.

If we had caught the right bus, we might’ve been on time.

Take note: mixed conditionals

Mixed conditionals combine the structure of type 2 and type 3 conditionals when the time (past, present and future) referred to in the if and result clauses are not the same.

Mixed conditionals can refer to: 

• something that didn’t happen in the past and the result of that condition in the present
  
  If you hadn’t left the map at home, we wouldn’t be lost. 
  (You left the map at home in the past. We are lost now.)
  
  
• something that won’t happen in the future and the result of that condition on the past
  
  If I weren’t going on holiday next week, I could have accepted that offer of work.
  (I am going on holiday in the future which is why I didn’t accept the offer of work in the past.)