What is a conditional sentence?
Conditionals are sentences with two clauses; one of them is a condition (normally introduced by «if» or «unless») and the other is a consequence. If the words «if» or «unless» appear at the beginning of a sentence, there is normally a comma separating both clauses. Take a look at this example:
If I go to bed early, I won’t be tired tomorrow.
I won’t be tired tomorrow if I go to bed early. (no comma needed)
In the previous sentence, there’s the condition (If I go to bed early,) and the consequence (I won’t be tired tomorrow.).
Note how we can use «if» or «unless» almost interchangeably, provided we make some necessary modifications:
Unless I go to bed early, I will be tired tomorrow.
I will be tired tomorrow unless I go to bed early. (no comma needed)
As you can see, «unless» normally involves a negative meaning, so one of the clauses needs to change from negative to positive or vice versa. Normally, we represent the equivalence between «if» and «unless» like this: Unless = If….not.
In general, there are 4 basic types of conditional sentences which are used depending on the context or the meaning we want to express. The difference between these sentences is, apart from the meaning, the tenses that we use. Let’s see these 4 types:
Zero Conditional Sentences
We use the zero conditional when we want to talk about something that is general knowledge or a universal truth. For example:
If you heat water, it boils.
The grass doesn’t get wet unless it rains.
The structure we use is: If/Unless + present, + present.
First Conditional Sentences
We use the first conditional when we want to talk about something that is possible and that it is likely in the context we are saying it.
If I study hard, I’ll pass the exam.
I won’t tell anyone if you don’t want.
The structure we use is: If/Unless + present, + future.
For the first conditional structure, we should also take into account the following:
- In some cases, we can use the modal verb «can» instead of «will».
If I study hard, I can pass the exam.
- In the consequence clause, we can find an imperative structure. Do not confuse this structure with the zero conditional.
If you get home early, give me a call.
Second Conditional Sentences
We use the second conditional when we want to talk about something that is possible but unlikely in the context we are saying it. We also call this type of conditional «hypothetical» or «unreal conditional», as it refers to a hypothetical or unreal future.
If I won the lottery, I’d buy a huge mansion.
If I went to the US, I would like to visit San Francisco.
The structure we use is: If/Unless + past simple, + would+infinitive.
For the second conditional structure, we should also take into account the following:
- In some cases, we can use «could», «may» or «might» instead of «would».
If I won the lottery, I might buy a huge mansion.
Now read the sentences below and choose the correct option for each gap.
Third Conditional Sentences
We use the third conditional when we want to talk about something that is impossible because it’s something we cannot change because it’s in the past. Therefore, this is another type of «unreal conditional», because it refers to a hypothetical or unreal past.
If I had studied French, I would have visited France already.
I wouldn’t have done that if you had asked me not to do it.
The structre we use is: If/Unless + past perfect, + would have+past participle.
For the second conditional structure, we should also take into account the following:
- In some cases, we can use «could», «may» or «might» instead of «would».
If I had studied French, I might have visited France already.
- This conditional is not very common at B1 level.
Now test yourself with the sentences below.
Mixed Conditional Sentences
Mixed conditionals are sentences that mix the first part of a type of conditional and the second part of another type. This is due to the fact that regular conditional sentences are unable to talk about reality as it is in all cases. For instance, we can talk about a past situation that affects a present or future event:
If I had studied French, I would live in France now.
In this case, we are mixing a third-type condition (If I had studied,) with a second-type consequence (I would live in France now.). Another common mixed conditional is when a present or constant situation affected us somehow in the past:
If I liked eating pasta, I would have ordered spaghetti.
In this last sentence, we are mixing a second-type condition (If I liked pasta,) with a third-type consequence (I would have ordered spaghetti.).
There are many types of mixed conditionals, but it is important to know the basic types before moving on to mixed-type sentences. You can learn more about mixed conditionals here.
