Упражнение 1. Choose the right tense form. 1. Nina has been learning/has learned English for 2 years. 2. The birds have already flown/have been flying to the South. 3. They have known /have been knowing him for many years. 4. Mike has forgotten/has been forgetting to learn the poem. 5. The children have been watching/have watched cartoons for 2 hours. 6. The train has just come/has been coming. 7. We haven't been having/ haven't had a holiday for 5 years. 8. She has been teaching/has taught at this school for twenty years. 9. David has been painting/has painted in his studio since 10 o'clock. 10. Mary and Sam have collected/ have been collecting stamps for 3 years. 11. Their parents have been/have being friends since their childhood. 12. Dave has been/ has been being a student for 2 years.

Решение:

1. Nina has been learning English for 2 years. (Present Perfect Continuous используется, чтобы подчеркнуть длительность действия.)
2. The birds have already flown to the South. (Present Perfect используется, когда важен результат, а не процесс.)
3. They have known him for many years. (Present Perfect используется для выражения длительного состояния.)
4. Mike has forgotten to learn the poem. (Present Perfect используется, чтобы сказать о завершенном действии, результат которого важен.)
5. The children have been watching cartoons for 2 hours. (Present Perfect Continuous используется, чтобы подчеркнуть длительность действия.)
6. The train has just come. (Present Perfect используется для выражения только что завершенного действия.)
7. We haven't had a holiday for 5 years. (Present Perfect используется для выражения опыта к настоящему моменту.)
8. She has been teaching at this school for twenty years. (Present Perfect Continuous используется, чтобы подчеркнуть длительность действия.)
9. David has been painting in his studio since 10 o'clock. (Present Perfect Continuous используется, чтобы подчеркнуть, что действие началось в прошлом и продолжается до сих пор.)
10. Mary and Sam have been collecting stamps for 3 years. (Present Perfect Continuous используется, чтобы подчеркнуть длительность действия.)
11. Their parents have been friends since their childhood. (Present Perfect используется для выражения состояния, которое началось в прошлом и продолжается до сих пор.)
12. Dave has been a student for 2 years. (Present Perfect используется для выражения состояния, которое началось в прошлом и продолжается до сих пор.)