<p>Perhaps as [a consequence of] warfare [that erupted] when natural resources became scarce, many of Easter Island's large stone statues, called Moai, [have been toppled] by the islanders [themselves] 3 centuries ago.</p>
<h2>Answer is C. I thought it was D. Explain why C is grammatically wrong and D is right!</h2>
<ol>
<li>The prices of either of the cars seem to be well worth it</li>
<li>The price of either of the cars seems to be well worth it</li>
<li>Either of the cars seems to be well worth their price</li>
<li>Either of the cars seem to be well worth the price</li>
<li>Either of the cars seems to be well worth its price</li>
</ol>
<p>Why is the answer the 5th choice? I literally could not rule out any of these... lol.</p>
<h2>IS EITHER ALWAYS SINGULAR OR IS IT BASED ON WHAT IT IS MODIFYING??</h2>
A is wrong because “prices” should be “price” because “either” is singular.
B is wrong because of the ambiguous pronoun reference “it”.
C is wrong because “their” should be “its” because “either” is singular.
D is wrong because “seem” should be “seems” because “either” is singular.
E is correct.</p>
The present perfect tense (“[they] . . . have been toppled”) does not focus on the event; it focuses on the present consequences of the event.</p>
<p>The simple past tense (“[they] . . . were toppled”), on the other hand, focuses on the event in the past. The sentence is trying to describe an event that occurred in the past–that’s it. It is saying that the stone statues were toppled 3 centuries ago. You can’t say that they “have been toppled” 3 centuries ago because the “3 centuries ago” strictly denotes and requires the simple past (“were toppled”), because it has to do with a explicitly stated point in the past. Similarly, you can’t say, “When I was 5, I have been . . .” nor can you say “When I was 5, I had been. . . .” By stating a time period, you force the sentence to be narrowed to simple past, simple present, or simple future.</p>
<p>D is grammatically correct, as “themselves” emphasizes that the islanders toppled their own statues. For example, “the cooks themselves ate the food at the ceremony.”
The first two are incorrect because you don’t say that the prices are “well worth it”; you say that the cars themselves are “well worth it.” “Well worth it” is an expression that means “useful,” “worth the price.”
The third and the fourth one are incorrect because “either” is always singular as a noun and thus everything that refers to it must be singular. “Either of the cars seems to be well worth its price.”</p>
In the case of that particular sentence, no, you can’t talk about something in the conditional and then talk about it (in the same frame) in the past. The past tense assumes that we are in the present tense and looking back in time. The “would” in this sentence assumes that we are in the past and looking forward into the past. . . . If that makes any sense.</p>