"They will not want to open a book anymore after their exams."
Translation:Ils ne voudront plus ouvrir un livre après leurs examens.
Why is it ‘un’ livre not ‘de’ livre in a negative sentence? Grammar rule is: replace indefinite article with de in negative sentence, I thought. Genuinely unsure here! Have looked it up over and over again and find that I am right, but would like native French speaker to adjudicate if possible! I put ‘Ils ne voudront plus ouvrir de livre...’