I've forgotten my wallet at work. Now I can't buy food.
If I hadn’t forgotten my wallet at work, I could buy food
I’m not going to have a day off tomorrow because my boss asked me to go on a business.
If my boss hadn’t asked me to go on a business, I’d have a day off tomorrow.
His sister is so extravagant; she spent most of her money on clothes and expensive restaurants
If his sister weren’t so extravagant, she wouldn’t have spent most of her last money on clothes and expensive restaurants.