Breakdown of Tu ne dois pas coller ce tissu, tu dois le découper.
tu
you (informal singular)
ne
not (used before the verb)
pas
not (used after the verb)
ce
this (before a noun)
Questions & Answers about Tu ne dois pas coller ce tissu, tu dois le découper.
Why is le placed right before découper instead of before dois?
When a sentence has a conjugated verb followed by an infinitive (like dois + découper), the object pronoun goes immediately before the infinitive it belongs to. Since you are cutting it (le découper), the pronoun le goes right before the verb for "cut".
What does the le refer to in this sentence?
Why doesn't the negative ne ... pas go around the infinitive coller?
In French, the negative words ne and pas usually form a sandwich around the conjugated verb. Here, dois is the conjugated verb, so it becomes ne dois pas. The infinitive coller stays outside the sandwich.
Why use ce for "this" instead of cet or cette?