I know the rules for the First Conditional, Second Conditional and Third Conditional. I’m not sure about the Mixed Conditional. What is it and what is the grammar?
Maria, Italy

Hi Maria,

Conditionals are fairly easy if you think about the meaning of the verb tenses.
If you understand the first, second and third conditionals, then you know the meaning of the verb tenses.
The rules and grammar don’t help so much from now on.

First Conditional
Tenses are for things that really happen.

“If it rains (present simple), we’ll get (future simple) wet.”

So we use tenses for things that really happen and really will happen.

Second Conditional
We use past tenses for things we don’t believe will happen or are impossible.
We don’t have unreal tenses in English – we use the past instead.

“If I won (past simple) the lottery, I would (will in the past) marry you.”

The speaker is using “won” not “win” because he doesn’t believe he’s going to win the lottery, and he isn’t going to marry you. So don’t believe him!

Third Conditional
We can put a real past tense unreal, by putting it further into the past. We do it with the past perfect.
And we can make the present perfect unreal but using “would”, the past of “will”.
So we can talk about things that didn’t really happen, and are in the past.

            “If I had been (past perfect) a singer, I would have been (will in the past + present perfect) famous.”

I didn’t really become a singer, and I didn’t really become famous – but it was possible.

Mixed Conditionals
So you know how you mix verb tenses together to make real and unreal, past, and present.
Now you mix them as you want to.

There isn’t just one mixed conditional. There are lots. You invent them.

The most common mixed conditional is a condition in the past with a result in the present.

            “If I had been a singer, I would be rich!”
            The If clause is in the 3rd conditional, so it’s an unreal past, and ‘would be’ (2nd conditional) is an unreal present.
            Unreal past condition and unreal present result.

            “If he had been up the Eiffel Tower, he would know it’s in Paris.”
            He doesn’t know the Eiffel Tower is in Paris, so he hasn’t been up the Eiffel Tower.
            Unreal past condition, unreal present result.

            “If she had caught the train, she would be here by now.”
            Unreal past condition and unreal present result.

            “If I had done the homework, I would be ready.”
            Unreal past condition and unreal present result.

            This is an unreal past condition.
            “If I did the homework …” (2nd conditional) means “do it (now)”, but I’m not going to do it.
            “If I do the homework …” means “do it (now)”, and I am going to do it.

Here are some less common examples.

            “If he said that, he was lying.”
            Real past condition and past result. (These are not 1st, 2nd or 3rd conditional.)

            “If he said …” suggests a real past condition: he did say it.
            “If he had said …” (3rd conditional) suggests it’s unreal, so he didn’t say it.

            “If she has got on the plane, she’ll be in New York in the morning.”
            Real past condition and real future result.

            “If she had got (3rd conditional) on the plane, she’d be (2nd conditional) in New York in the morning.”
            Unreal past condition and unreal future result.

If you concentrate on the meaning tenses of the verbs, you will understand, and you will be able to make up your own mixed conditionals.