Please correct me if you see any mistakes. Thanks a lot.<br/><br/>By then, I had been working on the essay for 7 hours.<br/><br/>By then, I had worked on the essay for 7 hours.<br/><br/>( Which one sounds better?)<br/><br/>By 2001, I had worked on the project for 8 years. or<br/><br/>By 2001, I had been working on the project for 8 years.<br/><br/>( Which one sounds better?)<br/><br/>By the time we broke up, we had lived more than 10 years.<br/><br/>By the time we broke up, we had been living more than 10 years.<br/><br/>( which one sounds better?)