Learn French: Quand ils manifesteront sans bruit, ils n'obtiendront rien. - When they demonstrate without noise, they will obtain nothing.

In French, when you use time conjunctions like quand (when), lorsque (when), or dès que (as soon as) to talk about an event that has not happened yet, the verb following them must be in the future tense. English uses the present tense here, which makes this a very common trap for learners!

Why is there no pas in ils n'obtiendront rien?

The word rien (nothing) is a negative word that pairs with ne (or n' before a vowel). When you use specific negative words like rien, jamais (never), or personne (nobody) to wrap around the verb, you must drop the pas.

How is obtiendront formed in the future tense?

It comes from the verb obtenir (to obtain/get). Like its root verb tenir (to hold), it has an irregular future stem: obtiendr-. To make it future tense for ils, you just add the standard ending -ont.

Could I say sans de bruit or sans le bruit instead of just sans bruit?

Usually no. After the preposition sans (without), French typically drops the article (like un, le, or de) when talking about a general concept or an uncountable noun. It translates literally to 'without noise'.