5. — What _______ they _______ (do) now? — They _______ (play) volleyball. — How long _______ they _______ (play) volleyball? — They _______ (play) volleyball for three hours.

Решение:

1. — What are they doing (do) now?
2. — They are playing (play) volleyball.
3. — How long have they been playing volleyball?
4. — They have been playing volleyball for three hours.

Ответ: are; doing; are playing; have been playing; have been playing.