USING UNLESS

The use of unless in conditional means if not. It means that unless is always bringing negative conditional since it brings negative meaning. Unless can be applied to all types of conditional without changing the purpose of the sentences.

Examples: 

Type 0:

If it is not one hundred degrees of Celsius, water doesn’t boil.

Unless it is one hundred degrees of Celsius, water doesn’t boil.

If they don’t move, don’t hurt them.

Unless they move, don’t hurt them.

Type 1:

If the weather doesn’t get better, I will just stay home.

Unless the weather gets better, I will just stay home.

If they are not coming, I will leave this city forever.

Unless they are coming, I will leave this city forever.

Type 2:

If he didn’t call me, I wouldn’t come here.

Unless he called me, I wouldn’t come here.

If the water didn’t block our way, we would be there on time.

Unless the water blocked our way, we would be there on time.

Type 3:

If she hadn’t got married earlier, she would have been happier.

Unless she got married earlier, she would have been happier.

The tiger won’t eat if he had not been hungry.

The tiger won’t eat unless he had been hungry.