OG11-9与Prep-1-28 although 用法的疑惑

9.     Sunspots, vortices of gas associated with strong electromagnetic activity, are visible as dark spots on the surface of the Sun but have never been sighted on the Sun’s poles or equator.

(A) are visible as dark spots on the surface of the Sun but have never been sighted on

(B) are visible as dark spots that never have been sighted on the surface of the Sun

(C) appear on the surface of the Sun as dark spots although never sighted at

(D) appear as dark spots on the surface of the Sun, although never having been sighted at

(E) appear as dark spots on the Sun’s surface, which have never been sighted on

Logical predication + Parallelism

The correct parallel structure in the original sentence emphasizes the contrast between where sunspots are found (are visible... Sun) and where they are not (have never been sighted ... equator). Sunspots is the subject of the sentence, are is the verb of the first part of the contrast and have been sighted is the verb of the second. (The adjective visible is a complement and is parallel to the past participle sighted.) Both parts of the sentence conclude with phrases indicating location. The contrast itself is indicated by the conjunction but.

A     Correct. This sentence clearly and correctly draws a contrast between where sunspots are found and where they are not.

B      Changing the modifying clause so that that never ... Sun distorts the meaning of the sentence; the contrast is lost

C     Although typically introduces a subordinate clause, which has a subject and a verb, but here there is no subject and sighted is not a complete verb   就是说Although 后面一定要跟完整的句子

D     Although usually introduces a subordinate clause, but there is no subject of the clause and having been sighted is not a complete verb phrase

E      The relative pronoun which should immediately follow its referent; here which illogically follows surface, and its intended referent, either sunspots or dark spots, becomes unclear

The correct answer is A.

Polio, although it is eradicated in the United States, it continues elsewhere and is able to be brought into the country by visitors.

E

(A) Polio, although it is eradicated in the United States, it continues elsewhere and is able to be

(B) Polio, although eradicated in the United States, it still continues elsewhere and can be

(C) Although still continuing elsewhere, polio has been eradicated in the United States and could be

(D) Although having been eradicated in the United States, polio still continues elsewhere and is capable of being

(E) Although eradicated in the United States, polio continues elsewhere and could be

希望大家讨论，谢谢

ad264,非常感谢。看了Og的解释后，我又去找了BY

发现如下解释：

状语从句的省略：

正确形式：表示时间、条件、转折等的连词(when/while/if/unless/although/even/though/even if) +形容词短语/-ing分词短语/-ed分词短语（逻辑主语等于句子主语）

错误形式：表示时间、条件、转折的连词+介词短语/名词短语

特殊情况：once 可以加介词短语/名词短语，whatever可以加名词短语构成状语从句省略。

搜索发现有老帖，但还是有疑问。希望能顶顶，有人路过给解答下 。

在如题的OG11-9中的D选项，如果按状语从句省略形式，也可以这样解释啊：

Sunspots appear as dark spots on the surface of the Sun, although never having been sighted at ....

although的主语和主句的主语是一致的。

如果按prep笔记上所说的having been done不能用来做分词修饰 那c选项中的although从句也满足定从省略形式呀。

希望哪位战友给解答下

我也支持一下,

OG11-9的C，OG11-68的E选项。OG11里面都说省略的状从不完整...这不似乎颠覆了prep里面的状从省略理论吗...