Using if clauses

It is important to realise that the word if can be used in many different ways, and there are many structures that can be followed- we will look at this in more detail later.

In a clause that follows if, we usually talk about uncertain events and situations- something which may or may not happen, something which may or may not be true. An if clause often refers to a condition- something that must happen first in order for the second event to happen. These are called conditional clauses.

• If it’s not raining, we will go to the park. 
• We will go to the park if it’s not raining.
• If you work hard, we will go out for dinner.
• We will go out for dinner if you work hard.

Notice that the if clause can go either at the beginning or the end of the sentence.

Here are some of the conditionals that could be used. Let’s take a closer look at the most common ones and see how they are formed.

Zero conditional 

The zero conditional is used for when the time being referred to is now or always and the situation is real and possible. It uses the present simple tense in both parts.

The zero conditional refers to facts that are generally true or scientific facts. The condition always has the same result. With zero conditional sentences the if can be replaced with when (because both express general truths) and the meaning of the sentence will be unchanged. 

The zero conditional is also used to give instructions, using the imperative in the main clause.

• If you heat ice, it melts.
• Ice melts if you heat it.
• If it rains, the grass gets wet.
• The grass gets wet if it rains.
• Plants die, if they don’t get enough water.
• If they don’t get enough water plants die.
• If you’re not sure what to do, ask me.
• Ask me if you’re not sure what to do.

In a zero conditional sentence the ‘if’ can be replaced by when.

• When you heat ice, it melts.
• When it rains, the grass gets wet.
• The grass gets wet when it rains.

First conditional or Type 1 conditional 

This type of conditional is used when referring to the present or future where a situation is real. This type of sentence uses the present simple to form the if clause and the future simple for the main clause.

These sentences are based on facts and are used to make statements about popular situations or the real world. The first conditional is often used to give warnings. The first conditional refers to a possible condition and its probable result.

• If you don’t hurry, you will miss the plane.
• We will miss the plane if you don’t hurry.
• If it rains today, you will get wet.
• You will get wet if it rains today.
• If you drop that plate, it will break.
• The plate will break if you drop it.

Second conditional or Type 2 conditional 

This type of conditional is used to refer to a time that is now or any time, and a situation that is unreal, these sentences are not based on fact. This type of sentence uses the past simple for the if clause and would/would not + verb for the main clause. 

The second conditional refers to an unlikely or hypothetical condition and its probable result. You can also form the second conditional using if I were.

• If you ate your dinner, you wouldn’t be hungry.
• You wouldn’t be hungry if you ate your dinner.
• If I spoke Spanish, I would be working in Spain.
• I would be working in Spain if I spoke Spanish.
• If I were younger, I would go skiing.
• I would go skiing if I were younger.

Third conditional or Type 3 conditional

The third conditional is used to refer to a time that is in the past and a situation that is contrary to reality. The facts they are based on are the opposite to what is expressed. This type of sentence uses the past perfect for the if clause and would have + past participle for the main clause.

It is used to refer to an unreal past condition and its probable past result. These situations are unreal and hypothetical, because it is now too late for the condition or its result to exist. These type of conditionals usually have some implication of regret or criticism, as the reality is often the opposite of what the sentence expresses.

• If you had studied harder, you would have passed the exam. (But you didn’t study so didn’t pass the exam.)
• You would have passed the exam if you had studied harder. 
• If I had accepted the job, I would have been working in America.
• I would have been working in America if I had accepted the job. (But I didn’t accept the job so I’m not working in America.)
• If I had known it was your birthday, I would have bought you a present. (But I didn’t know it was your birthday so I didn’t buy a present.)
• I would have bought you a present if I had known it was your birthday.
• If you had driven more carefully, you wouldn’t have had an accident. (But you didn’t drive carefully so had an accident.)
• You wouldn’t have had an accident if you had driven more carefully.