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题库 / GMATLA-SC-9
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.
and whether, presuming such life forms having left fossil traces to begin with, those traces can
and whether, if it is presumed that such life forms left some fossil traces to begin with, can those traces
and whether, presuming such life forms left fossil traces to begin with, those traces
and, presuming such life forms did leave some fossil traces to begin with, if they can
and, presuming such life forms to have left fossil traces to begin with, if they
首先排除DE直接因为语法的问题，B中IT没有指代，在AC中, A 中presuming插入语中也有语法的问题，所以选C。 但不明白的一点是Presuming的逻辑主语可以是those traces吗？
persuming... 在这个句子里作为伴随状语修饰的是 whether those traces still exist...这整个句子，因而没有所谓的明确的逻辑主语。
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