Grammar · Conditionals & Wishes
Unless, As Long As & Provided That
Unless, as long as and provided that add a condition without the word “if”. Learn them with the film The Princess Bride.
Grammar › Conditionals & Wishes › Unless, As Long As & Provided That
The rule in one sentenceunless means “if … not”, and as long as means “only if” – after both, use the present simple, even when you talk about the future.
About the film
The Princess Bride is a film from 1987. A grandfather reads a story to his grandson, who is ill in bed. The boy doesn’t want a love story unless it has some action – and this one has sword fights, giants and chases. In the story, Buttercup lives on a farm with Westley, a young farm boy. Westley will do anything for her, as long as she asks, and he always answers: “As you wish.”
What does it do?
These words add a condition to a sentence, like “if”. One part of the sentence only happens when the condition is true.
Unless means “if … not”. It names the one thing that can stop something. As long as means “only if”. It names the one thing that must be true. Provided (that) means the same as as long as, but it sounds more formal.
Look at the first tile. It means: if the story doesn’t have action, the boy won’t listen. Unless already has the “not” inside it, so the verb after it stays positive.
You will also hear other words with the same meaning as as long as:
If you don’t ask, Westley won’t help. Unless you ask, Westley won’t help.
The two sentences mean the same thing. But never say “unless you don’t ask” – unless already means “if not”.
Visual guide
Teacher Teddy’s illustrated guide to this rule is being drawn — the full swipe-through infographic will appear here soon.
How to make it
unless — “if … not”
Unless Buttercup asks, Westley does nothing.
The boy won’t sleep unless he hears the end of the chapter.
The main part can be negative. The part after unless stays positive.Will you read to me, unless you’re too tired?
Unless can make a friendly offer or question softer.as long as — “only if”
You can stay up late, as long as you finish your soup.
Fezzik is gentle, as long as nobody hurts his friends.
After as long as, a negative verb is fine.Can I listen, as long as I stay quiet?
Very common when you ask for permission.When to use each one
unless — the one thing that stops it
as long as — the one thing that must be true
Words that help: stop or must?
These words and phrases have the same meaning. They can help you choose.
unless → the thing that stops it
as long as → the thing that must be true
Common mistakes
❌ Unless you don’t ask, Westley won’t help.
✅ Unless you ask, Westley won’t help.
Unless already means “if not”. Don’t add another “not”.
❌ I’ll read the book, as long as you will stay awake.
✅ I’ll read the book, as long as you stay awake.
Use the present simple after as long as, even for the future.
❌ Everyone likes Westley unless the prince.
✅ Everyone likes Westley except the prince.
Before a noun on its own, use except. Unless needs a subject and a verb.
❌ The boy will enjoy the story unless it has sword fights.
✅ The boy will enjoy the story as long as it has sword fights.
He wants sword fights, so this is a thing that must be true. Use as long as.
One more thing
This part is a little harder. You can come back to it later.
“As long as” can also talk about time. Sometimes as long as means “for the whole time that”, not “only if”. The context tells you which meaning is correct.
✅ You can stay as long as you want. (for all the time you want)
✅ You can stay, as long as you’re quiet. (only if you are quiet)
And in formal English, provided that often appears in contracts and official rules.
Practice: choose the right word
Eight questions. Choose one answer. You get the answer, and why.
1. The boy won’t listen ___ the story has some action.
If the story doesn’t have action, he won’t listen → unless.
2. Westley will help, ___ Buttercup asks him.
Her asking must be true → as long as.
3. Unless you ___ early, you’ll miss the start of the film.
Unless already means “if not”, so the verb stays positive.
4. You can borrow my sword, as long as you ___ it back tomorrow.
Use the present simple after as long as, even for the future.
5. Everyone laughed ___ Vizzini.
Before a noun on its own, use except.
6. ___ that you have a ticket, you may enter the castle.
Having a ticket must be true → provided (that).
7. I’ll read one more chapter, ___ you’re too tired.
Being too tired is the thing that stops it → unless.
8. Fezzik is friendly, ___ nobody is unkind to him.
Nobody being unkind must be true → as long as.
Your turn
Choose one ending. Then listen to your sentence.
Every sentence here is correct. Pick the one that is true for you. Say it out loud too!
Keep going
More lessons
Practise listening at your level
Hear this grammar used for real — Intermediate English listening practice. Full movie reviews in slow, clear English, levelled for Intermediate learners. One new episode every week, free, with a transcript. IntermediateFree playlistWatch on YouTube