Inverted conditionals
1. If anyone should ask, please don't tell them it was me who told you.
Should anyone ask, please don't tell them it was me who told you.
2. If I had thought about it for longer, I think I would have got the answer right.
Had I thought about it for longer, I think I would have got the answer right.
3. They wouldn't be in this situation now if they had taken my advice.
Had they taken my advice, they wouldn't be in this situation now.