Ответ:

  1. It is nice to be back!
  2. What are their names?
  3. I am from Russia, not from Poland.
  4. They are not my friends, they’re my sisters.
  5. Are you a fairy?
  6. Who is the present from?
  7. Why are you sad?
  8. Mary and James are tall and slim.

Правило: am употребляется с I, is — с существительным или местоимением в единственном числе, are — с you и формами множественного числа.