You don't have to go to the party unless you want to.

Source: Tatoeba

Be quiet, or the baby will wake up.

Source: Tatoeba

Get up at once, or you will miss the 7:00 bus.

Source: Tatoeba

You'll never know unless you try.

Source: Tatoeba

Hurry up, or you'll miss the bus.

Source: Tatoeba

Hurry up, or you will miss the train.

Hurry up, or you'll miss the train.

Source: Tatoeba

Send for the doctor at once, or the patient may get worse.

Source: Tatoeba

Go at once, otherwise you will be late.

Source: Tatoeba

Don't argue with an idiot, or else people might not be sure which of you is really the idiot.

Source: Tatoeba

I never drink unless there's a big event of some kind.

Source: Tatoeba

Get up at once, or you will be late for school.

Source: Tatoeba