Unless is used to talk about conditions and possible results. It can replace "except if" or "only if" in sentences. The part of the sentence before "unless" is the condition, and the part after is the possible result if the condition is not met. Examples are given showing how unless can be used in both positive and negative sentences.

1. UNLESS
We can use unless in place of except if
and only if to talk about the conditions
under which something can happen.

2. Unless with a subject and verb means only if or except if in
positive and negative sentences. The other part of the
sentence gives the possible result.
possible result unless subject and verb
I'm not going to dance unless you ask me.
I won't go by car unless it's a long way.
someone has a
We can go to the park unless better idea.

3. subject and
unless possible result
verb
we're there by 8 we won't get
Unless
o'clock anything to eat.
Elena wants to we can go by
Unless
take a taxi bus.
you tell me who I will make you
Unless
broke the cup pay for it.