The third conditional is advanced English grammar. Here is a multiple-choice English test (below) to check your knowledge of how to use this 'unreal conditional'. We use third conditional sentences to talk about a 'different past'. In other words, we are thinking about how past events would/could/might have been different if some other past situation had been different. This past situation did not happen and we can not go back in time to change the past, so that's why the 3rd conditional is called an 'unreal conditional'.
The 'formula' for this type of sentence is...(click on image to enlarge)
Common grammar mistake
It is a common error for people to put the If and would together. So, keep the two parts of the sentence (the If clause and the would clause) separated from each other.
If you need more example sentences, please look at this this recent post about David Beckham with extensive unreal conditional grammar explanations and lots of example sentences. There is also a helpful table from that post at the bottom of this page, to act as a guide before you do the English test.
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