If Matt and Elena don't arrive at the party before 8 o'clock, they
won't get anything to eat.
Matt: Unless we're there at 8 o'clock we won't get anything to eat!
Unless is followed by a subject and verb, like this:
Matt: Unless we are there at 8 o'clock…
Unless means only if or except if. The second part of the sentence gives the possible result. Matt and
Elena will get something to eat only if they arrive before 8. Listen again:
Matt: Unless we're there at 8 o'clock we won't get anything to eat!
Here's another example:
Matt: We'll go by bus unless Elena wants to take a taxi.
They will go by bus except if Elena wants to take a taxi. Note that unless is used with a present tense, even when it has a future meaning. Here's another example:
Elena: I'm not going to dance unless you ask me.
Elena is only going to dance if Matt asks her.
Be careful with positives and negatives:
Matt: I'll go by car unless it's a long way
Elena: I won't go by car unless it's a long way
In the first one, Matt will go by car, except if it's a long way, in which case he'll fly, or take the train or something. In the second one, Elena will go by car only if it's a long way. If it's a short distance, she'll fly
or take the train. Listen again:
Matt I'll go by car unless it's a long way
Elena I won't go by car unless it's a long way
To recap, '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
We can go to the park unless someone has a better idea
unless -subject and verb -possible result
Unless we're there by 8 o'clock we won't get anything to eat
Unless Elena wants to take a taxi we can go by bus
Unless you tell me who broke the cup I will make you pay for it