Hello, I wonder if this sentence is correct:<br/><br/>"Based on that information, the conclusion has been drawn that Stonehenge <b>wasn't</b> built by Druids."<br/><br/>Maybe I should have used " hadn't been" instead of " wasn't"?<br/><br/>And by the way, what preposition do we use here: <b>at/in</b> that phase/period ?<br/><br/>Thank you.