TT-GWD 2-34,找了半天没找到讨论

NASA’s methodical approach to the exploration of Mars has not yet answered the questions of whether biological life forms ever emerged on Mars and whether, presuming such life forms having left fossil traces to begin with, those traces can still exist in some moist recesses of the cold and arid planet.

A.      and whether, presuming such life forms having left fossil traces to begin with, those traces can

B.      and whether, if it is presumed that such life forms left some fossil traces to begin with, can those traces

C.      and whether, presuming such life forms left fossil traces to begin with, those traces

D.      and, presuming such life forms did leave some fossil traces to begin with, if they can

E.       and, presuming such life forms to have left fossil traces to begin with, if they

大家选A还是C？

我认为选A

C有两个问题，presuming后边缺少that，those traces缺少can

对于A我的理解 presume sth doing sth， doing->having left 不知道可不可以这样用

查了longman。presume没有加doing的

presume sth

presume to do sh

presume sb\sth to be sb\sth

presume (that)

A中用完成时的进行时态（having done）来修饰名词，错误！应该改为that从句的形式

不过C没有can和that也不够好

open to discuss

我觉得因该是A
        and whether, presuming such life forms having left fossil traces to begin with, those traces can  "having left fossil traces to begin with"是 modify forms的。语感上没有错误。语法上我不知道。 但是can是不可以随便去掉的，遵照原文。

GMAT中不能用现在完成时的ing形式做后置定语，所以A肯定不对

C又少了can。。。

事实上我在OG中看过现在分词作定语的情况，只是不记得具体在哪里了

我同意4楼的看法，觉得A似乎更合适

can确实不能随便去掉，而且此处假设语气很强烈啊

同意选C

首先PREP中也有宾语从句不加that的，不过我不记得哪题了，就是那个saying（that）。。省略了。

can这里不需要的，因为并列的话，whether需要时态一致的，prep中也有这样的句子，whether+实意动词时态 and whether+同样的时态，也讲究对称的。

Behind this methodical approach is the enduring question of whether life ever emerged on Mars and left some fossil traces, and whether it still exists in some moist recesses of this cold, arid world.

It doesn't need past perfect sense, nor does it need can. "Can" specifiies the ability to do something. Fossil traces have no life. whether they can be preserved relys on the natural environment not themselves.  

Vote for C.