总结得相当好，赞一个！补充点我的想法，欢迎讨论
关于220语法笔记上面的解释，to be honest我觉得解释很不好，贴一下OG的解释：
This sentence describes twosequentially ordered
indicators by which the results of a company's cost-
cutting measures can be seen. The first indicator to
be identified, a 5 percent increase in profits,
occurred after the indicator mentioned next. The
sentence therefore needs to clarify the sequence by
presenting the first-identified indicator in a clause
with a verb tense that indicates a later time period
than the verb tense in the clause presenting the
second-identified indicator. The subject of the
relative clause, which,refers to the plural noun
profits, so subsequent pronouns referring to these
profits must also be plural.
A The verb tenses do not distinguish between
the times at which these indicators occurred;
the singular it does not agree with theplural
profits.
B The verb tenses do not distinguish between
the times when the indicators occurred; the
singular it does not agree with theplural
profits.
C Correct. The verb tenses clearly indicatethe
sequence of events.
我认为语法笔记
“B. after it had fallen时态上没有问题，可以与over the last two years搭配，但是不如after falling简洁”
这个解释不准确。把B选项代入原句
The results of the company's cost-cutting measures are evident in its profits,
B. which had increased five percent during the first three months of this year after it had fallen
那么整个句子的时态就是：一般现在时，过去完成时，过去完成时
发现问题了么？就是时态间存在gap——跳跃了过去时。Manhattan那本书里面说过在一个句子里面时态不能有"gap" （p111),比如不能：
The scientist BELIEVED that the machine WILL BE wonderful.
所以B选项时态就是错的。改成which increased ... after it had fallen就对，也表明了时间顺序的逻辑关系，也可以是which have increased ... after it fell。这两者之间我更倾向于后者（前者也不能说错吧），原因是从逻辑上理解，
The results ... are evident in its profits, which
主句are一般现在时，用现在完成时能够很好的表达“过去的事情对现在产生影响”这个逻辑含义，所以更preferred。
lz的理解：
after doing 作状语，表达其修饰的动作之前发生的动作，其修饰的动词和after后面的动词动作发出者要一致。如此表达最能体现出二者的先后关系。
我同意lz的理解，然后补充Manhattan上面对现代分词的解释(p.237，建议详细阅读这一节，太经典了）：
Present participles get their tense from the main verb in the sentence.
那么看C选项：
C. which have increased five percent during the first three months of this year after falling
就说这里用同样的时态来表示"after"前后的两个事件（increase和fall），但是"after"这个词明确说明了两个事件的先后顺序。没有问题！
lz提到以下，我觉得很赞
AlienX: after having done something是不可能对的
1)after已表示the sequence of events.没有必要用having done来表示前后
2)可是after someone/something has/have done something是acceptable; 如果变成after someone/something did something也可以
补充我的理解：
1)直接after doing就可以了，不要after having done。因为doing作为present participle自动套用主句时态（See Manhattan）且强调了先后顺序，而after having done把后面的时态改成了完成时，不合理。
2)这里after后面跟的是clause，不是直接跟present participle。另外的话题了
我的理解很简单：如果是after+noun. (concrete noun, action noun, complex gerund)，那么就不用考虑noun的逻辑主语问题。如果是after+simple gerund(即present participle)，那么就必须考虑逻辑主语问题。
我随便编个例子：
After the discovery of North America, the Europeans hoped to find gold on this land.
这里europeans显然不是discover的主语，但是这句子没问题，因为discovery作为名词存在，咱并不在乎谁做的这个discovery。
如果句子改成：After discovering North America, the Europeans hoped to find gold on this land. 这就不对了！因为after后面接现代分词(present participle，也即simple gerund)，就必须要这个动作的主语是主句主语（且时态和主句一致），那么显然the Europeans不是discover的主语。
如果改成After the discovering of North America, the Europeans hoped to find gold on this land。那么这句子就不存在逻辑主语问题，因为"the discovering of .."不再是simple gerund而是complex gerund，即作为名词。当然，这个句子比较awkward，因为已经有discovery这个action noun存在，因此要把discovering改成discovery。看！又回到了最早的那个正确句子。
1 after doing 相关问题
220. (GWD-24-8, OG12-86)The results of the company's cost-cuttingmeasures are evident in its profits, which increased five percent during thefirst three months of this year after it fell over the last two years.A. whichincreased five percent during the first three months of this year after it fellB. whichhad increased five percent during the first three months of this year after ithad fallenC. whichhave increased five percent during the first three months of this year afterfallingD. with a five percent increase during the firstthree months of this year after falling (C)E. with a five percent increase during the firstthree months of this year after having fallen
答案选C，但解释上有点问题我不明白：下面是语法笔记上对于B 和C 的解释：B. after it had fallen时态上没有问题，可以与over the last two years搭配，但是不如after falling简洁C. Correct；afterfalling简洁，状语从句的省略求助讨论：可是我不理解为什把after doing理解为状语从句的省略。我觉得这里不是省略!!!
状语从句的省略：从句主语和主句主语一致，并且包含be。。。从句主语和be可以省略。when，although ，等词引导时间状语从句，让步状语从句等时，可以用这种形式来简洁表达。 但是 如果把这里的after doing 理解为 after it have/had been falling。我觉得也不能清晰的表达出原文所想表达的时态先后关系。而且如果这里 fall是进行时表达一直在下降，这里也是不对的吧。 我的理解：
after doing 作状语，表达其修饰的动作之前发生的动作，其修饰的动词和after后面的动词动作发出者要一致。如此表达最能体现出二者的先后关系。
The best way to extract the flavor from saffron threads is to soak them in liquid after pounding them 。。。这里pounding作状语，修饰的是soak。 虽然整句话都没有出现pound的动作发出者，但soak和pound二者逻辑上的动作发出者一致。 另外提一句： AlienX: after having done something是不可能对的
1)after已表示the sequence of events.没有必要用having done来表示前后
2)可是after someone/something has/have done something是acceptable; 如果变成after someone/something did something也可以
2 after+n的逻辑主语问题。
需要再讨论，不知道对不对
看两个例子： prep16： Less than 35 years after the release of African honeybees outside Sao Paulo, Brazil , their descendents, popular known as killer bees had migrated as far north as Southern Texas。。。 85：In 1945, after a career as First Lady in which she shattered expectations more audaciously than either Abigail Adams or Dolly Madison ever had been, Eleanor Roosevelt was appointed a delegate to the United Nations General Assembly by President Harry S Truman.
Bmore audaciously than either Abigail Adams or Dolly Madison, President Harry S Truman had Eleanor Roosevelt appointed to be a delegate to the United Nations General Assembly.
D. with an audacity never mathed by Abigail Adams or Dolly Madison, Eleanor Roosevelt was appointed a delegate to the United Nations General Assembly by President Harry S Truman. 我的理解：after +n 究竟是否存在逻辑主语问题，要看前面的名词而定。 如16题，after 后面接了一个事件，句子主干再说这个事件之后的事情。主干的事情不一定是发出那个事件的人作的另一个事。
而且这里release 是action n，反而避免了after releasing 的逻辑主语问题。（这里可见 Manhattan的 v-a-n原则不是万能的哦）
85题：after +后面的名词明显是不完整的，缺少一个能和 那个n 对应的 发出者。这种情况下，要考虑after的逻辑主语问题。
总之：after +n后面的逻辑主语问题是句子逻辑意思而定。
一般来说，after +n 表达一个能够对很多人造成影响的的事件，而不是某个小土鸡作的鸡毛蒜皮的小事，一般after+n 是不需要动作发出者的。
好像有点抽象，举个例子：
（1）after 退休， 老王干了啥。。
（2）二战之后，老王干了啥。。
好像after就这两点比较烦，其他情况想起来再补充哈。。
欢迎大家讨论，拍砖。
-- by 会员 12604698 (2012/1/15 14:16:56)
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发表于 2012-1-15 14:16:56
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发表于 2012-1-17 07:55:20
