Breakdown of Tu dois isoler ce fichier de peur qu'il n'infecte ton ordinateur.
tu
you (informal singular)
il
he
l'ordinateur
the computer (m)
ce
this (before a noun)
Questions & Answers about Tu dois isoler ce fichier de peur qu'il n'infecte ton ordinateur.
Why is there an n' before infecte? Does it mean the file won't infect the computer?
No, the sentence is not negative! This is the ne explétif (an extra or filler ne). It is often used after expressions of fear or prevention like de peur que to emphasize that you want to avoid the action. It doesn't translate to 'not' in English.
Is it mandatory to include this ne after de peur que?
No, the ne explétif is formal and completely optional. In everyday spoken French, you will usually just hear de peur qu'il infecte. Including it makes your French sound very elegant and is mostly found in written texts or careful speech.
Is infecte in the present indicative or the subjunctive here?
It is in the subjunctive mood. The conjunction de peur que (for fear that) always requires the subjunctive because it introduces an uncertain, hypothetical outcome that you are trying to prevent. For regular -er verbs like infecter, the present indicative and subjunctive forms happen to look exactly the same for the il form.
Why does the second part of the sentence use il when talking about a file?