A. had belonged / sold
Feedback 1. According to the meaning it would be correct to use the Past Perfect Continuous for the first part because it is obviously important for the speaker to emphasize the duration of the process here: for 3 years. But we remember that non-continuous verbs cannot be used with '-ing'. So it is correct to choose the Past Perfect Tense. 2. We use the Past Simple for completed actions in the past.