Ответ:

Решение:

  1. John has painted two pictures. (John - 3-е лицо, единственное число. Present Perfect: has/have + V3)
  2. Jill has fed her bird. (Jill - 3-е лицо, единственное число. 'feed' - неправильный глагол, V3 - fed)
  3. The children have played computer games. (The children - множественное число. Present Perfect: has/have + V3)
  4. It's hot in the room. I have opened the window. (I - 1-е лицо, единственное число. Present Perfect: has/have + V3)

Ответ: 1. has painted, 2. has fed, 3. have played, 4. have opened.