请教大家一个to do用法的问题

aeoluseros

嗯，继续观望:-D

小花呱

OG上找到两个例子：
OG10-34的explanation  Choices C and D are needlessly wordy, and D requires that before North Americans, to be grammatically complete.

这个例子来自解释，而不是原题。

185. The recent surge in the number of airplane flights has clogged the nation's air-traffic control system, to lead to 55 percent more delays at airports, and prompts fears among some officials that safety is being compromised.

(A)to lead to 55 percent more delays at airports, and prompts

(B)leading to 55 percent more delay at airports and prompting

(C)to lead to a 55 percent increase in delay at airports and prompt

(D)to lead to an increase of 55 percent in delaysat airports, and prompted

(E)leading to a 55-percent increase in delays atairports and prompting

OG10的解释：
This question poses two major problems: parallel structure and precision of expression. In E, the best choice, parallel structure is maintained in the participial phrases introduced by leading and prompting, and the phrase 55-percent increase in delays conveys the meaning more accurately than does the phrase 55 percent more delay(s) in A and B. Also, choice A lacks parallelism. In C and D the infinitive phrase to lead to ... is less idiomatic than the participial phrase leading to .. .'_ Choice C uses the singular delay where the plural is needed to indicate an increase in the number of delays; the phrase increase in delay has no exact meaning.


OG11、12的解释：

Parallelism + Diction

The intent of the sentence is to show two effects of the surge in flights. These effects should be stated in parallel ways, instead of the construction to lead ... and prompts ... used in the original sentence. Using participial phrases introduced by leading and prompting solves this problem. The phrase 55 percent more delays is not as clear as the phrase a 55 percent increase in delays.

ATo lead and prompts are not parallel; 55 percent more delays is not clear

B55 percent more delay is unclear

CTo lead and prompt are not parallel; the meaning of increase in delay is not clear

DA participial phrase introduced by leading is preferable to the unclear infinitive phrase to lead to; an increase of 55 percent in delays is awkward and wordy

ECorrect. Leading and prompting are parallel in this sentence; the phrase a 55 percent increase in delays is clear
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OG里并没有说to do不可以用，只是说了unclear, unidiomatic，而对于leading也只说了preferable，说明语法上leading和to do都可以，只是用了infinitive phrase造成了含义上的unclear。

不知道这下能否下结论了。但我更为相信“不定式可以在句尾做单独结构”。因为不能在句尾做单独结构并没有很合理的解释，只是当初XDF还是刘振民说出的一个观点，并没有说明本质的evidence。

-- by 会员 aeoluseros (2010/5/6 9:46:15)

斑竹，这个OG12-30
30. For members of the seventeenth-century Ashanti
nation in Africa, animal-hide shields with wooden
frames were essential items of military equipment,
a method to protect warriors against enemy arrows
and spears.



(A) a method to protect

(B) as a method protecting

(C) protecting

(D) as a protection of

(E) to protect
中的E，选项OG给的解释是：although the infinitive to protect would work if it were not preceded by a comma,it cannot act as a nonrestrictive adjectival phrase modifying items.
应该说不定式前加，是不对的。
Ps，我想问问，选项C为什么按照OG的话说可以表示the purpose of the items of military equipment.这点不是说-ing是做主语的伴随状语或者是伴随结果么，那么修饰的应该是animal-hide shields with wooden frames.怎么成了修饰items的目的了呢？？

superbat28

to 小花呱，我不知道你这个protecting的问题明白没有~我就在这里再说下好啦~

ing结构前面有逗号的时候，优先考虑其作状语，其修饰的对象是前面整个句子主干。但ing做状语又有很多种区分：
若主句是主系表结构，ing结构是对前面主系表结构的句子做的一种补充说明，此时ing结构不表伴随，不表结果，只是表示一个补充说明的  意思。

而当前面是主谓宾的时候，逗号+ing形式可做伴随动作，可做结果状语。若表伴随，其伴随的是主句动词，但必须保证主句主语是ing形式的动作发出者。若表结果状语，其修饰前面整个主句，并无逻辑主语的问题，但是前面主句再改作名词结构后，可以作为ing结构动作的发出者。举例如下(OG12 Q47)：
Five sea eagles left their nests in western Scotland, bringing to 34.... (这道题是OG最经典的bringing做结果状语，修饰前面整件事)
把主句变为名词，即是The leave of the five sea eagles brings....  可见是这个leave这个事情（把left名词化）作为brings的真正主语。

关于蓝色字体中，是曼哈顿上给出的一种说法~我觉得比较形象和实用，可作为一个辅助的判断标准~

关于to do的问题，我今晚一定要找出个答案~哈哈~

小花呱

我觉得这个补充说明这个点，感觉不是那么准确。
-ing在句末，前面有逗号时，首先的作用是对前面的词进行修饰。 如果前面是个非名词的时候将转为考虑是否是做状语，（伴随或者结果。伴随要求的是和句子主语一致。）
这道题的Protecting 应该是对前面的items of military equipment修饰。
这个用法比如og12-21(D )，og12-38, og12-55(D) 等。

抓抓sandra

bat，小花狐，
我觉得这个protecting应该理解成状语or定语都是可以说得通的，因为这个protecting是主语shields的动作，也是items的功能（因为shields were items，二者相同），而不是主语动作的伴随。我之前的理解是“主系表，ing”的ing并不是一定要是状语，句末逗号隔开的ving完全可以当做定语，只要不会发生歧义即可。比如这里，理解成状语或者定语，一点都不影响句子的逻辑含义，所以可以。

抓抓sandra

我推测，主系表的系动词不是be的时候，用逗号加ving就不适合理解成定语，因为这个时候理解成定语还是状语句意大不相同。

superbat28

我推测，主系表的系动词不是be的时候，用逗号加ving就不适合理解成定语，因为这个时候理解成定语还是状语句意大不相同。

-- by 会员 抓抓sandra (2011/8/20 7:55:03)

给个例子？~主系表，系动词不是be还能是什么~~？appear,smell这些词？
可是如果是这些词的话，后面是adj啊，比如She appears good. 就算句尾有【逗号，ing】形式，这个也不可能定语啊，前头没名词。
抓抓想的是什么情况？我一时没反应过来……