关于一个句子结构的语法讨教，感谢

Q17:

Scholars who once thought Native American literatures were solely oral narratives recorded by missionaries or anthropologists now understand this body of work to consist of both oral literatures and the written works of Native American authors, who have been publishing since 1772.

1. Scholars who once thought Native American literatures were solely oral narratives

2. Scholars thinking of Native American literatures once solely as oral narratives, and
3. Scholars who once had thought of Native American literatures solely as oral narratives and
4. Native American literatures, which some scholars once thought were solely oral narratives

5. Native American literatures, which some scholars once, thinking they were solely oral narratives

正确为A,没有选择A，因为认为结构scholars who once thought 。。。were的结构不正确。不明白：（

我分析这个句子结构是：

Scholars who once thought ....，真正的主语是非划线部分的now understand 才对吧？

我错误选择C，因为实在选不出来了，c时态的确也有问题

讨教！

非常感谢：）

再讨教2题：我想了好久，没想明白，有哪位有思路讲解一下，万分感谢：）

Section12

Q19:

Possible long-term consequences of the “greenhouse effect,” the gradual warming of the Earth’s climate, may include melting the polar ice caps and a rising sea level.

1. may include melting the polar ice caps and a rising sea level

2. may include the melting of polar ice caps and the rising sea level

3. may include polar ice caps that are melting and sea levels that are rising

4. include melting the polar ice caps and sea levels that are rising

5. include melting of the polar ice caps and a rise in sea level

错误选择B，正确为E

Q22:

On account of a law passed in 1993, making it a crime punishable by imprisonment that a United States citizen hold gold in the form of bullion or coins, immigrants found that on arrival in the United States they had to surrender all of the gold they had brought with them.

1. On account of a law passed in 1993, making it a crime punishable by imprisonment that a United States citizen hold

2. With a law passed in 1933 that makes it a crime punishable by imprisonment that a United States citizen hold

3. A law passed in 1933 that made it a crime punishable by imprisonment for a United States citizen holding

4. Because of a law passed in 1933 making it a crime punishable by imprisonment for a United States citizen to hold

5. Due to a law being passed in 1933 that makes it a crime punishable by imprisonment for a United States citizen to hold

错误选择C，但是还是不明白为什么答案为B?

recorded by missionaries or anthropologists作为过去分词短语修饰narratives，B和C里的and都不对，另外感觉B中once的位置不好；句子主干的动词是understand，所以D和E中的Native American literatures作为主语错。

A中who once thought Native American literatures were solely oral narratives recorded by missionaries or anthropologists 整个是个定语从句修饰Scholars，这个定语从句中先套了一个宾语从句，thought(that)Native American literatures were ...宾语从句中的宾语oral narratives 又被过去分词短语recorded by 修饰。

这个宾语从句的that被省略现象，我不确定，欢迎大家讨论。

Possible long-term consequences of the “greenhouse effect,” the gradual warming of the Earth’s climate, may include melting the polar ice caps and a rising sea level.

这题其实是个逻辑搭配的考点，C选项给出了两个部分的典型错误，may include polar ice caps that are melting and sea levels that are rising，effect应该搭配一个变化过程或者结果，而不是参与变化的事物本身。E，include melting of the polar ice caps and a rise in sea level

Q22我的选择是 D，感觉because of比with更能说明因果关系

prefer B

Q22的主詞是immigrant,與a law的關係是因為law在19xx年通過所以immigrant發現....

with是because作為副詞子句的改寫，這樣做可以將句子寫的更簡潔.

如果是D,我認為because of後面不應該接一個子句，最多只能接個名詞片語，所以應當不能選D

谢谢各位