单选题 32. At a certain period in Earth's history, its atmosphere contained almost no oxygen, although plants were producing vast quantities of oxygen. As a way of reconciling these two facts, scientists have hypothesized that nearly all of the oxygen being produced was taken up by iron on Earth's surface. Clearly, however, this explanation is inadequate. New studies show that the amount of iron on Earth's surface was not sufficient to absorb anywhere near as much oxygen as was being produced. Therefore, something in addition to the iron on Earth's surface must have absorbed much of the oxygen produced by plant life.
In the argument given, the two portions in boldface play which of the following roles? ______

A、 The first is a claim made by the argument in support of a certain position; the second is that position.
B、 The first is a judgment made by the argument about a certain explanation; the second is that explanation.
C、 The first expresses the argument's dismissal of an objection to the position it seeks to establish; the second is that position.
D、 The first sums up the argument's position with regard to a certain hypothesis; the second provides grounds for that position.
E、 The first is a concession by the argument that its initial formulation of the position it seeks to establish requires modification; the second presents that position in a modified form.

【正确答案】 D

【答案解析】 D：第一部分确实是一个观点，即前文的解读不充分。选项中的“某个假说”便是指氧气被铁吸收。第二部分是原因，同时两个黑体部分为同向，因此第二部分是第一部分的观点所基于的原因。
A：首先，第二部分是原因而非结论，可直接判定该选项错误。其次，第一部分用来反驳前文给出的观点：氧气被铁吸收。
B：第一部分确实是对某种解释的评价，这种解释指的是前文观点：氧气被铁吸收。评价是“这种解读不充分”。但是第二部分并不是被第一部分所评价的那个解释。
C：首先，第二部分是原因而非结论，可直接判定本选项错误。其次，本文并不存在对其想要确立的观点(即铁以外的东西吸收了氧气)的反驳。
E：文章本身不存在让步语气的句子，而且第一部分所在句子中有however这个句间取反的标志，其语气远远强于让步。