<p>Quincy took Dan to Derek's home (for a visit A),
(never imagining B) that five years (would pass C)
Before (seeing D) Derek again.
The answer is "D" can someone tell me why?</p>
The question you have posed in this thread is an excellent example of clearly ambiguous possession of the gerundial phrase. Whose seeing do we mean? Quincy’s, I presume, but this is not grammatically evident. Acceptable corrections include “Quincy’s seeing Derek again” and “Quincy would see Derek again.”</p>
<p>I foresee a potential point of confusion here: The syntactic conflation of participles and gerunds. Consider this form:</p>
<p>Though not seeing Derek again for five years, Quincy…
That the seeing is Quincy’s is unambiguous in this reformation of the sentence, whatever follows “Quincy.” The difference is that the modification is participial here: The subject of the clause following the phrase “Though not seeing Derek again for five years” is what that phrase modifies adjectively.</p>
<p>In the sentence as originally written, however, “before seeing Derek again” is gerundial and not so flexible. The syntax does not clarify the relationship, so we need to use a possessive modification or subordinate the clause.</p>
<p>(Again, I want to qualify: This description is potentially hard to understand. I don’t have a good sense of how much background knowledge on readers’ parts I am assuming. Please ask if further help is needed on this topic.)</p>