How do you specifically use partitives in French?

I’m in French I, and my teacher told me to use partitives (du, de la, de l’, des) every time except for after negative expressions (n’___ pas) and expressions of quantity (beaucoup, un peu, etc.), where it becomes de or d’. After aimer, detester, adorer, and preferer, you use le, la, or les (J’aime les legumes). When you say something like “Je n’aime pas ____ pommes, do you use de or les. If you use les, is my teacher’s rule wrong?
No; what I mean is, while you normally say: “J’aime les fruits”, what goes in the blank when you say “Je n’aime pas ____ fruits”? My teacher said it was de.