He has been studying the environment for over ten years., He _ the environment for over ten years. (study), We have been working hard to build nesting boxes., We _ hard to build nesting boxes. (work), It has been raining for two days., It _ for two days. (rain), He has been donating money to Greenpeace for a long time., He _ money to Greenpeace for a long time. (donate), The government has been trying to reduce pollution for years., The government _ to reduce pollution for years. (try), I have been volunteering to clean out ponds for a year now!, I _ to clean out ponds for a year now! (volunteer)

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