Ответ:

Правило: little употребляется с неисчисляемыми существительными, а few — с исчисляемыми существительными во множественном числе. Артикль a придаёт значение «немного, некоторое количество».

  1. I have a little free time today, so we can chat.
  2. Hurry up! We have very little time before the train leaves.
  3. She knows a little French, just a couple of basic words.
  4. Don't worry, we have a little milk left for your cereal.
  5. He is sad because he has few friends at his new school.

Ответ: 1) a little; 2) little; 3) a little; 4) a little; 5) few.