<p>Quincy took Dan to Derek's home [for a visit], [never imagining] that five years [would pass] before [seeing] derek again. [No error]</p>
<p>Why is [seeing] the error?</p>
<p>i think it should be "she would see" but i don't know why....like if you're looking for specific grammar rules and references and stuff like that, i'm sorry but i really can't help you.</p>
<p>It's ambiguous. You don't know whether it's Quincy or Dan who won't see Derek for 5 years.</p>