[讨论]Prep 1-28,

这个题为什么不选B呢？E的COULD是过去时态，和整个句子的时态不符啊。

XDF的一个老师说，COULD ,MIGHT在GMAT里没有表示委婉的意思，只表示是过去时态

28.   (26003-!-item-!-188;#058&002229)

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

(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

B: "Polio" and "it", 两个主语.

Don't follow the rule 100%. The goal is to pick the BEST answer, not the perfect answer, among the 5 choices.

Prep Grammar Note says: having been eradicated in C is incorrectly used.
    

I think it is okay to use although having been done here - past perfect tense plus passive mode.

Anybody can tell me why, thanks?

I get it.

The phrase after/although having been done is wrong. We should substitute after/although done for it anytime.

To AlienX:

From any grammar book, we can see that as a participle, having been done is incorrect anywhere. It is redundant and needs to be replaced with done.

This is my note taken months ago:

The Participle (Present Participle/ Past Participle)

1.       用法：作副词或形容词，Present Participle：表主动，Past Participle：表被动；

2.       Tense and Voice of The Present Participle：

doing                                    being done（被动加进行）

having done                        having been done（表被动加完成，但过于罗嗦，没有done好）

3.       Tense and Voice of The Past Participle：

    done（表被动加完成）                 

eg2: Most of the artists ______ to the party were from South Africa.

A) invited    B) to invite    C) being invited    D had been invited

析：选A。D项不是非谓语，因为不是have而是had，变成have been done也没有done简洁。