Paleontologist: About 2.8 million years ago, many species that lived near the ocean floor suffered substantial population declines. These declines coincided with the onset of an ice age. The notion that cold killed those bottom-dwelling creatures outright is misguided, however; temperatures near the ocean floor would have changed very little. Nevertheless, the cold probably did cause the population declines, though indirectly. Many bottom-dwellers depended for food on plankton, small organisms that lived close to the surface and sank to the bottom when they died. Most probably, the plankton suffered a severe population decline as a result of sharply lower temperatures at the surface, depriving many bottom-dwellers of food.
In the paleontologist's reasoning, the two portions in boldface play which of the following roles?
Paleontologist: About 2.8 million years ago, many species that lived near the ocean floor suffered substantial population declines. These declines coincided with the onset of an ice age.【现象(不算错)】 The notion that cold killed those bottom-dwelling creatures outright is misguided, however;【观点】 temperatures near the ocean floor would have changed very little.【evidence】 Nevertheless, the cold probably did cause the population declines, though indirectly.【结论】Many bottom-dwellers depended for food on plankton, small organisms that lived close to the surface and sank to the bottom when they died.【principal】 Most probably, the plankton suffered a severe population decline as a result of sharply lower temperatures at the surface, depriving many bottom-dwellers of food.【evidence】
In the paleontologist's reasoning, the two portions in boldface play which of the following roles?
(A) The first introduces the hypothesis proposed by the paleontologist; the second is a judgment offered in spelling out that hypothesis.
(B) The first introduces the hypothesis proposed by the paleontologist; the second is a position that the paleontologist opposes.
(C) The first is an explanation challenged by the paleontologist; the second is an explanation proposed by the paleontologist.
(D) The first is a judgment advanced in support of a conclusion reached by the paleontologist; the second is that conclusion.
(E) The first is a generalization put forward by the paleontologist; the second presents certain exceptional cases in which that generalization does not hold.
D——(d) is backwards. (d) states that #1 supports #2, when in fact the argument is written in such a way that #2 supports #1.
【Ron對A解釋】 the conclusion of this passage is "the cold probably did cause the population declines, though indirectly". once you figure out that's the conclusion, there are only two answer choices left in play: (a) and (b), the only two choices that actually say that's the conclusion (the "hypothesis proposed by the paleontologist"). note that "a generalization" and "an explanation" are not going to represent conclusions. a "judgment" could be a conclusion, but not in the case of choice (d), because there it's followed immediately by "...in support of X". between (a) and (b), you don't have to think that hard. choice (a) says that the second boldface is for the conclusion, while choice (b) says the second boldface is against the conclusion. since the former is true - the second boldface is the rationale behind the paleontologist's hypothesis - you go with (a).