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60. One of the more reliable methods of determining regional climatic conditions in prehistoric periods is to examine plant pollen trapped in glacial ice during ancient times. By comparing such pollen samples with spores take from modern vegetation, scientists can figure out approximately what the weather was like at the time of pollen deposition. Furthermore, by submitting the prehistoric samples to radiocarbon dating techniques, we can also determine when certain climatic conditions were prevalent in that portion of the globe.
Which one of the following may be inferred from the information in the passage?
A. The earth has undergone several glacial periods.
B. Radiocarbon dating can be corroborated by glacial evidence.
C. Similarities between prehistoric and contemporary climates do not exist.
D. Pollen deposition is a fairly continuous process.
E. Certain flora are reliably associated with particular climatic conditions.
INFERENCE question is very similar to ASSUMPTION in that both are required conditions in the argument. So inference is not a conclusion itself of the argument. It is one condition that must be true for the conclusion to hold. The line of reasoning can be as follows:
Argument: A à B. Ask for inference C. The links are A à B à C. Or Not C à Not B. A and B are the premise and conclusion in the argument respectively. C is the inference.
No. 60 is a good example. What the passage says is that scientists can figure out the weather condition in ancient times by examine the pollen from those times. So the hidden premise is that there is a connection between groups of plants and climatic conditions. If E is not true, and there is no connection between plants and climatic conditions, the statement that scientists can find out the climatic conditions by studying pollen can not hold.
So, for INFERENCE questions, you should treat it the same way as ASSUMTION question. First, understand the conclusion, or the statement in this question. And find the REQUIRED condition in the choices. To test the answer, use “NOT” and put it back in the argument to see if conclusion still holds.
Let’s take a look at the rest of the choices.
A: Irrelevant. Scientist can use pollen to find out the climatic conditions no matter how many times the earth has undergone glacial periods. When you see a choice with words expressing “degree” or “times” like rarely, most, many, less, several, probably, very, none, etc., pay attention to what the passage says. You need to make sure that these words can be inferred from the passage.
B. Irrelevant. The argument says that using radiocarbon on the samples can get further information. What B says is that glacial evidence supports radiocarbon dating. In another words, glacial evidence proves what radiocarbon dating finds out. It is not hinted by the argument or required for the conclusion.
C. Irrelevant to the statement. Use “not” to test.
D. Looks like an answer. But the statement is not about the continuity of climatic conditions. So D is irrelevant. |
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