$1$. If i were rich, i would live in a big house
Unless i were rich, i wouldn't live in a big house
$2$. If sandra got her camera, she could take a photo
Unless sandra got her camera, she couldn't take a photo
$3$. If she didn't bought a lot of clothes, she would have money
Unless she didn't bought a lot of clothes, she wouldn't have money
$4$. If we got calculator, we could work this out quicker
Unless we got calculator, we couldn't work this out quicker