tu ne dois

must not

→ tu
phrase Uncommon #19,645
must not Used to give a strong negative instruction or warning: "you must not" / "you shouldn’t." Usually followed by another verb in the infinitive, often with ne...pas, ne...jamais, etc.
FR: Tu ne dois pas ouvrir cette porte.
EN: You must not open that door.

Tu ne dois jamais parler.

You must never speak.

— La vie est belle (1997)

Tu ne dois plus souffler dans ce coquillage.

You must not blow into that shell anymore.

— Le Chant de la mer (2014)

Tu ne dois en aucun cas ouvrir la boîte.

You should not open the box under any circumstances.

Sonia, tu ne dois pas douter de lui.

Sonia, you mustn't doubt him.

— Guerre et Paix (1968)

Tu ne dois rien prendre au sérieux, sauf le menu, bien sûr.

You shouldn't take anything seriously, except the menu, of course.

— La grande bellezza (2013)

Tu ne dois jamais perdre ton sang-froid.

You must never lose your cool.

Tu ne dois rien croire de ce que Tom raconte sur moi.

You mustn't believe anything Tom says about me.

Tu ne dois en aucun pas sortir dehors aujourd'hui.

You mustn't go outside today under any circumstances.

Toi non plus, tu ne dois pas t'en approcher.

You mustn’t go near it either.

— Le Garçon et le Héron (2023)

Tu ne dois lire que quelques pages de ce livre.

You only need to read a few pages of this book.

Grand frère, tu ne dois rien faire d'illégal.

Big brother, you must not do anything illegal.

— Lust, Caution (2007)

Tu ne dois rien dire!

You mustn't say anything!

— La vie est belle (1997)

Je sais que tu ne dois surement pas me comprendre.

I know you probably don't understand me.

— Avatar (2009)

Tu ne dois jamais me mentir.

You must never lie to me.

Tu ne dois plus penser au passé.

You must stop thinking about the past.

— Voyage à Tokyo (1953)

Woo-sung, tu ne dois jamais nous oublier.

Woo-sung, you must never forget us.

— Les Bonnes étoiles (2022)

Ce sont nos affaires, tu ne dois surtout pas y toucher!

These are our belongings, you absolutely must not touch them!

— L'Orphelinat (2007)

Aussi, tu ne dois jamais avoir peur.

Also, you must never be afraid.

— Rome, ville ouverte (1945)

Maintenant que tu es grand, tu ne dois pas te comporter ainsi.

Now that you're grown up, you shouldn't behave like that.