Select all sentences that correctly use a third conditional for an unreal past situation.
If we had sent the invoice earlier, the client would have paid before the deadline.✓Correct answer
If the pilot would have checked the gauge more carefully before departure, she would have noticed the fault.
If the referee had heard the whistle, he would have paused the match.✓Correct answer
If Hana had brought her violin, she would perform at last night's concert.
Explanation
The invoice and whistle sentences both combine a past-perfect condition with a would-have past result. The inspection sentence puts would have in the if-clause, while the violin sentence uses a non-past result for last night's concert.