Ответ:

Решение:

  1. Peter has already helped his mother to make fruit salad. (Peter - 3-е лицо, единственное число)
  2. Nick and Sam have not drawn a nice picture for their sister yet. (Nick and Sam - множественное число)
  3. My mother has already made a beautiful dress for my bithday party. (My mother - 3-е лицо, единственное число)
  4. My brother and I have cleaned the kitchen. (My brother and I - множественное число)
  5. The girl has not decorated her room yet. (The girl - 3-е лицо, единственное число)
  6. They have washed the dishes and watered the flowers. (They - множественное число)
  7. You have already done all your homework. Well done! (You - может быть как единственное, так и множественное число, в данном случае используется 'have')
  8. I have just started a new game. (I - 1-е лицо, единственное число)
  9. His parents have bought Mike a nice present. (His parents - множественное число)
  10. Vic has just come to Ottawa. (Vic - 3-е лицо, единственное число)

Ответ: 1. has, 2. have, 3. has, 4. have, 5. has, 6. have, 7. have, 8. have, 9. have, 10. has.