PREP里面有两道关于时态的问题，临考前请大家帮忙。

Luluisland

以下是引用skylighting在2007-5-7 1:08:00的发言：

我觉得第二题要关注一下previsouly这个词

sth they had not previously considered possible和sth not considered a previous possibility这两句话的意思和侧重点不太一样, 前者的意思是专家们以前没有觉得更好的控制有可能，后者把previous放在possibility前面，就变成了修饰possibility的了，并且整个这个句子的表达方式就很奇怪，a previous possibility-之前的可能性？不make sense嘛.

另外，previously经常表达的是“在。。。之前”的意思，如果没有previously,那可以说 sth they didn't consider possible, 但是加了previously, 结合前面说了这个项目的成功已经stimulated了专家们to pursue, 那这里就用过去完成时就没问题。我印象中是previously 一般放在句首，比如说，previously in Prison Break, blah blah blah, 或者放在句子中间修饰名词，比如说，a plan previously formed,一旦放在句子中间形容人主动发生的某个动作的时间时，大多数都用过去完成时的。

个人感觉阿，仅供参考，不知道说清楚了没有,我估计我考试要碰上这两道题也会错

同意！分析的真透彻。第一题也是，引用NN：

很多情况下，过去时间由上下文表示出来，不需要表示过去时间的状语。该题中，分号后面是have now realized，强调now，用了现在完成时，分号前面的long强调与现在的对比，用过去的时态较合理。
            

YY_lalala

这样子讲我觉得又复杂化了。have now realized强调谁不关键，关键是它本身提供了怎样的一个时点。强调now不错，但按照这个思路往下，那表示的时间点到底是过去还是现在？分号前过去的时态OK，但是过去的时态和过去完成时是有本质差别的，过去完成时一定是过去的过去。有了过去，才能有过去的过去。按ls提到的说法，就又回到了我最开始提出的问题：强调now的have now realized和分号前面的过去的过去，在时间轴上不延续、有gap

欢迎拍砖

YY_lalala

以下是引用Luluisland在2007-5-7 1:27:00的发言：
第二题大概想通A为啥不对啦。SC笔记里指出

A: GMAC偏好：如果能用名词替代一个名词性从句，优先选名词，比如something, probability, likelihood等；

而且这里关键是the other infections用的不对

前半句我个人忽略，呵呵，偏好这东西，难说

后半句我同意，同认为是关键错因，one... the other，这里如果没有the我认为A也是挺好的选项

让转头来得更猛烈些吧～

julianfl

skylighting说的很有道理哈。：）

而且我做完了PREP SC发现GMAC确实有一些偏好，比如说非常喜欢用同位语，好几道题目，看到一个句子后面带一个名字加修饰结构，马上就可以排除其他的选项，这样做题的速度可以提高一些：）还有就是Lulu说的名词性从句和名词的问题，GMAC也比较倾向名词，因为简洁。就算有例外，我想“仁慈”的GMAC也会在别的地方给出明显的瑕疵，让你引起注意。如果都没有，那我就认倒霉了。

还有对于时态变化的题目，“上帝般”的GMAC在很多时候也会同样在其他地方给与你排除的根据：）都没有的情况下，我在考试的时候就准备这样去做了：

（1）如果主从句是连续动作或同时发生的动作，不应该有时态的变化。

（2）如果主从句涉及到了一个的结果影响另一个的发生或者状态，那么就应该有时态变化，被影响方向后推一个时态。

到这个时候没有办法了，只能找这么个解释安慰一下自己了。：）

julianfl

PREP里面还有两道关于时态变化的题目，也一起贴上来备给案吧。

PREP2SC_147

Australian embryologists have found evidence that suggests that the elephant is descended from an aquatic animal, and its trunk originally evolved as a kind of snorkel.

(A) that suggests that the elephant is descended from an aquatic animal, and its trunk originally evolved

(B) that has suggested the elephant descended from an aquatic animal, its trunk originally evolving

(C) suggesting that the elephant had descended from an aquatic animal with its trunk originally evolving

(D) to suggest that the elephant has descended from an aquatic animal and its trunk originally evolved

(E) to suggest that the elephant is descended from an aquatic animal and that its trunk originally evolved

这道题目应该就是主句结果影响从句的发生的例子吧。所以主句完成，从句一般现在。

C里面除了其他的瑕疵，就时态来讲，也把主从句相互的影响搞反了。

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PREP2SC_082

In a blow to those who still harbored the illusion that E-mail exchanges are private, a watchdog group recently uncovered a trick for enabling an interloper to rig an E-mail message so that this person will be privy to any comments that a recipient had added as the message is forwarded to others or sent back and forth. 

(A) who still harbored the illusion that E-mail exchanges are private, a watchdog group recently uncovered a trick for enabling an interloper to rig an E-mail message so that this person will be privy to any comments that a recipient had added

(B) who had still been harboring the illusion that E-mail exchanges are private, a watchdog group recently uncovered a trick for enabling an interloper to rig an E-mail message so that this person was privy to any comments that a recipient might have added

(C) who still were harboring the illusion that E-mail exchanges are private, a watchdog group recently uncovered a trick enabling an interloper to rig an E-mail message so that this person is privy to any comments that a recipient would add

(D) still harboring the illusion that E-mail exchanges are private, a watchdog group recently uncovered a trick that enables an interloper to rig an E-mail message so that this person will be privy to any comments that a recipient might add

(E) still harboring the illusion that E-mail exchanges had been private, a watchdog group recently uncovered a trick that will enable an interloper to rig an E-mail message so that this person was privy to any comments that a recipient might add

这道题时态的变化看的最清楚，uncovered a trick… enables an interloper…. this person will be

主句和从句之间的关系是层层影响和递进的，所以先用过去，再用现在，后用将来就说得通顺了。最后用might add并不是时态而是语态的原因，表委婉。

[此贴子已经被作者于2007-5-7 10:19:53编辑过]