If it rains tomorrow, we will stay at home. (Unless) → Unless it rains tomorrow, we will not stay at home.

If Nam gets the job, he can earn a lot of money. (Should) → Should Nam get the job, he can earn a lot of money.

Hurry up or we'll miss the bus. (if) → If you don't hurry up, we'll miss the bus.

Don't drink too much coffee or you will feel ill. (If) → If you drink too much coffee, you will feel ill.