Ответ:

  1. stepfather — stepmother
  2. brother-in-law — sister-in-law
  3. nephew — niece
  4. half-sister — half-brother
  5. mother-in-law — father-in-law
  6. grandson — granddaughter
  7. great-grandfather — great-grandmother
  8. ex-husband — ex-wife
  9. widow — widower
  10. twin sister — twin brother

Answer: 1 stepmother; 2 sister-in-law; 3 niece; 4 half-brother; 5 father-in-law; 6 granddaughter; 7 great-grandmother; 8 ex-wife; 9 widower; 10 twin brother.