1. Sandra can't take a photo because she hasn't got her camera.
→ If Sandra had got her camera, she could take photo.
2. She buys a lot of clothes, so she has no money.
→ If she didn't buy a lot of clothes, she wouldn't have no money.
3. I have to work tomorrow evening, so I can't meet you.
→ If I didn't have to work tomorrow evening, I could meet you.
4. It's raining so we can't have lunch in the garden.
→ If it weren't raining, we could have lunch in the garden.