<li>By the time the operation was completed, five surgeons spent over 20 hours performing more than a dozen procedures.</li>
</ol>
<p>the answer says the underlined portion is wrong. i am guessing its because it has to be “had spent” but i dont understand why it has to be “had spent”</p>
<p>2.By the time the movie had finished, neither Eric nor his daughters was able to stay awake because of the boredom caused by the film’s inferior plot.</p>
<p>the correct replacement of the underlined is supposed to be “neither Eric nor his daughters were able to stay awake because of the boredom caused by the film’s inferior plot.” But isn’t that wrong and the original correct? since neither…nor makes the subjects singular shouldn’t the sentence stick to “was” rather than “were”</p>
<p>In the first one, the surgeons spent the 20 hours BEFORE the operation was completed, therefore the verb has to reflect this. In order to portray time before a past verb, you have to use ‘had’.</p>
<p>I’m not as certain on the second one, but I think common usage dictates that in a “neither…nor”, the subject closest to the verb dictates its number. Because daughters is closer, the verb becomes plural. (This may be wrong, it’s what I found by googling “neither…nor”)</p>
<ol>
<li><p>The surgeons carried out a continuous action into the past up until the surgery was completed. In order to reflect this the pluperfect tense must be used.</p></li>
<li><p>With neither…nor, the verb takes the form of the noun closest to the verb; in this case “daughters” makes it plural.</p></li>
</ol>