1、The filibuster on voting-rights legislation went on for three days and nights; senators slept when they could on benches in the hall.
×nights; therefore, it meant that senators would sleep when possible.
原句没错，两句完整，罩子没有问题。而下面的选项，it的出现使得主语混乱。
2、The programmers always talked of having too much to do, but in truth they had a lesser amount of work to do than their colleagues.
they had less work to do than
×their work was the least among
原句繁琐。下面的选项前后主语不一致，而正确选项避免了以上两个问题。
3、In Germany, foresters discovered that trees killed by acid rain had begun to die four years earlier, even though the trees had shown no signs of disease then.
×earlier without any signs of disease shown then
原句没错，even though是状从罩没有问题。而下面的错误是由于主语不一致加上无缘无故的被动。
4、In the wild, pygmy chimpanzees are found only in an inaccessible region south of the Zaire River, since such is the case, very few are in captivity.
and so no more than a few are in captivity
× and very few are in captivity because of that
原句因为没有罩子所以错了。而错误选择是由于可以变成so的形式，不需要and… because of that. 正确答案中and so是一个罩子。
5、Beginning photographers may choose from among several camera types, there is one which is best for their particular interests.
one of which is
×and one is
原句因为没有罩子错。错误选择中one指代不清。正确答案中看似没有罩，其实one of which就是定从罩which的变体。
6、Enzymes are among the oldest known chemical compounds, as they actually are nonliving protein molecules.
Enzymes, among the oldest known chemical compounds, actually are nonliving protein molecules.
原句错误是因为上下句没有逻辑关系不应该用as。
7、The author, taking the reader on a chronological journey through her native land, skillfully combining history and legend with fragments of fiction.
The author takes the reader on a chronological journey through her native land, skillfully
×The reader is taken on a chronological journey through the author’s native land by skillfully
原句错误是因为插入句之后还是从句，就没有了谓语。错误选项是因为主语是reader，后面skillfully combining就不是作者而是reader了。正确选项助于统一，谓语正确。
8、Television’s programming difficulties, already made acute by rising costs, threatens to become even more severe as a result of lobbying by special-interest groups.
already made acuter by rising costs, threaten
×already made acute by rising costs, threaten
原句错误因为谓语用了单数但主语是复数。正确词组是made acute。
9、The information age has ushered children into a global society, this situation causing educators to lament a lack of texts that explain the diversity of cultures.
a situation causing educators to lament
×which is the cause of educators lamenting
原句因为没有罩子而错。错误答案因为the cause of后面应该是句子。正确答案是一个很完美的定语从句省略，原句是(which is) a situation (that is) causing educators to lament
10、One result of the fire department’s new contract is that they can no longer offer overtime pay on weekends.
As one result of its new contract, the fire department can no longer offer overtime pay on weekends.
×One result of the fire department’s new contract is that they can no longer offer overtime pay on weekends.
原句和错误选择都是因为主语是单数却用了they。正确答案很完美。
11、If we compare the number of alligators with the Gila monster over time, we see that the alligator is in decline.
A comparison over time of the numbers of alligators and Gila monsters shows that alligators are
×Comparing the number of alligators and the Gila monster, we see that alligators are
这一题是对比对象一致的诠释。对比对象以the为标志，只有正确答案中the numbers of alligators and Gila是两个动物的数目比较。
12、Archaeologists say that the Pueblo village of Acoma, which is 7,500 feet above sea level and 400 feet above the valley floor, is the oldest continuously inhavited spot in the United States.
×located 7,500 feet high above sea level while having measured 400 feet above.
原句没错。错误选择里面while having measured太别扭。
13、For all their talk about ecology, major companies have so far spent very little to fight pollution.
原句没错。For all their talk固定搭配。
14、We generally think of Canada as the northern neighbor of the United States, and more than half of the states extend farther north than Canada’s southernmost point.
States; however, more than half of the states extend
×States, but more than half of the states extending
原句因为前半句有generally think，后半句应该是反驳，但是却用了and。错误答案中but引导的句子没有了谓语。正确答案无论是罩子、谓语和中心都是完美的。
15、When we were cleaning the garage, my sister and I found the old soccer ball in a dark corner we used to play with when we were young.
in a dark corner the old soccer ball we used to play with when we were young
原句错误是因为修饰语应该紧跟在被修饰词后。而原句中成为了“我们和黑暗的角落玩”。正确答案将地点状语提前，解决了这个问题。
16、A thick growth of sunflowers standing ten feet tall, their brown heads dropped over the fence with the weight of their seeds.
stood ten feet tall, their brown heads drooping
原句错误，因为两句中间缺少罩子。正确答案中，后面一句因为出现分词而成为从句。
17、In 1853 African American residents founded the San Francisco Athenaeum; its library and museum served as the hub of Black intellectual life in the region.
×their library and museum serving
原句正确。罩子没有问题，罩子后的句子也是完整的。而错误选择中的没有谓语。
18、Were I to be granted a whole month in which to do whatever I wanted, I would travel throughout Africa and see as much of that continent as I could.
原句正确。这是虚拟倒装，原句是If I were to be granted。
19、Henry Wadsworth Longfellow was a descendant of John and Priscilla Alden, whose romance he celebrated in the narrative poem “The Courtship of Miles Standish.”
×having celebrated their romance
原句没有错，主语清晰。而错误选择中，having celebrated前面不止一个人，就使得主语不清，可以是Henry celebrated也可以是他父母celebrated。
20、Bridget worried that she might not be able to bring back many souvenirs were she to take only one suitcase on vacation.
原句正确。同样是虚拟倒装。原句是Bridget worried that if she were to take only one suitcase on vacation she might not be able to bring back many souvenirs。
