24. He **has been studying** the environment for over ten years.
25. We **have been working** hard to build nesting boxes.
26. It **has been raining** for two days.
27. He **has been donating** money to Greenpeace for a long time.
28. The government **has been trying** to reduce pollution for years.
29. I **have been volunteering** to clean out ponds for a year now!
Объяснение: Present Perfect Continuous используется для описания действий, которые начались в прошлом и продолжаются до сих пор. Формула: has/have + been + V-ing.