Ответ:

  1. I wanted to cook potatoes. So I bought some.
  2. Do you need any milk?
  3. Are there any oranges in the cupboard? — No, there aren’t any.
  4. There are some new CDs in the shop. I want to listen to some.
  5. I want to buy stickers. I haven’t got any.
  6. Would you like some of this cheese? I’d have some.
  7. There are a lot of mushrooms in the forest. I’m going to gather some.

Перевод: some используется в утвердительных предложениях, any — в вопросах и отрицаниях.