while做连词后面难道不应该接一个完成的句子吗？只有A有谓语动词，BCDE都是少谓语动词的，所以为什么不能选A呀

mark，统计枚举

类比。错选A，没看请说的是两种褪黑素的区别，以为是褪黑素和其他药物的区别。仔细！

不同于一般的填空题（complete）--一般是以果寻因（complete argument...since/because）,本题要求用一个具体的现象（fact）去解释一个抽象的概念（principle）。
关键词：illustrated by the “fact“ that 。
解决此类题的关键在于弄清楚题干里的principle到底是什么意思。通过读题，作者通过the more...the more...和great...great...两个结构道出了一个原则：风险越大，（所寻求的）收益越大。
其实由于题中的“：”存在，我们完全可以只读“：”后面的结构（相较前面的更简单）。

helr，求讲解B为什么错误啊

b的were written 和outnumber 的主语都是lettres,所以outnumber那句省略了主语，这样想不对吗

E. The second boldface section presents not the historian’s conclusion but rather the
scholars’ conclusion, about which the historian expresses misgivings.

B E 纠结：
E. The second boldface section presents not the historian’s conclusion but

unless这个词，是真的让我转了不少弯；
What must be true in order for this cycle to occur?
unless = if not
提问句的意思是：如果下列那项不真，CYCLE就不会发生；= 如果下列哪项真，CYCLE就会发生

C的逻辑是 材料成本的变化属于通货膨胀里的一种

C Presumably the cost of materials was factored into the previous year’s contractual price, and the
percentage increase allowed by historical costing will likely reflect any increases in the cost of
materials.

If the original
contract price accommodated the contractors’ inefficiencies, the government’s
overpayments for these inefficiencies are simply perpetuated, and money continues to
be wasted. Additionally, historical costing assumes costs only go up, never down.

B Correct. If bollworm damage on non-bioengineered cotton is worse than usual this year, then
bollworm infestation in general is simply worse than usual, so pesticide resistance does not need
to be invoked to explain the bollworm attacks on the bioengineered cotton

第一遍看完所有选项，感觉没一个合适的；之后就选个最相关的，也只能是B

d 中的called a sea为什么不是过去分词做定语

a的which covers 为什么不是 跳跃修饰the landlocked caspian

这题的意思是说两个俱乐部的成员是有重叠的吗？

求讲解

Ron: as for your other question, this isn't really a perfect tense, because it's actually not a tense at all -- it's an infinitive.
probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms

完全看不懂