阅读理解 In 1971 researchers hoping to predict earthquakes in the short term by identifying precursory phenomena (those that occur a few days before large quakes but not otherwise) turned their attention to changes in seismic waves that had been detected prior to earthquakes. An explanation for such changes was offered by "dilatancy theory," based on a well-known phenomenon observed in rocks in the laboratory: as stress builds, microfractures in rock close, decreasing the rock's volume. But as stress continues to increase, the rock begins to crack and expand in volume, allowing groundwater to seep in, weakening the rock. According to this theory, such effects could lead to several precursory phenomena in the field, including a change in the velocity of seismic waves, and an increase in small, nearby tremors.
Researchers initially reported success in identifying these possible precursors, but subsequent analyses of their data proved disheartening. Seismic waves with unusual velocities were recorded before some earthquakes, but while the historical record confirms that most large earthquakes are preceded by minor tremors, these foreshocks indicate nothing about the magnitude of an impending quake and are indistinguishable from other minor tremors that occur without large earthquakes.
In the 1980s, some researchers turned their efforts from short-term to long-term prediction. Noting that earthquakes tend to occur repeatedly in certain regions, Lindh and Baker attempted to identify patterns of recurrence, or earthquake cycles, on which to base predictions. In a study of earthquake-prone sites along the San Andreas Fault, they determined that quakes occurred at intervals of approximately 22 years near one site and concluded that there was a 95 percent probability of an earthquake in that area by 1992. The earthquake did not occur within the time frame predicted, however.
Evidence against the kind of regular earthquake cycles that Lindh and Baker tried to establish has come from a relatively new field, paleoseismology. Paleoseismologists have unearthed and dated geological features such as fault scarps that were caused by earthquakes thousands of years ago. They have determined that the average interval between ten earthquakes that took place at one site along the San Andreas Fault in the past two millennia was 132 years, but individual intervals ranged greatly, from 44 to 332 years.

单选题 11.The passage is primarily concerned with

A、 explaining why one method of earthquake prediction has proven more practicable than an alternative method
B、 suggesting that accurate earthquake forecasting must combine elements of long-term and short-term prediction
C、 challenging the usefulness of dilatancy theory for explaining the occurrence of precursory phenomena
D、 discussing the deficiency of two methods by which researchers have attempted to predict the occurrence of earthquakes
E、 describing the development of methods for establishing patterns in the occurrence of past earthquakes

【正确答案】 D

【答案解析】Main idea
To answer this question, focus on what the passage as a whole is trying to do. The first paragraph describes a method for predicting the occurrence of earthquakes, and the second paragraph explains problems with that method. The third paragraph describes a second method for predicting the occurrence of earthquakes, and the fourth paragraph explains problems with that method. Thus, the passage as a whole is primarily concerned with explaining the deficiencies of two methods for predicting the occurrence of earthquakes.
A The passage does not compare the practicability of the two methods.
B The passage does not discuss combining long-term and short-term methods.
C Only the first half of the passage discusses dilatancy theory; the second half discusses a different method for predicting the occurrence of earthquakes.
D Correct. The passage describes two methods for predicting the occurrence of earthquakes and explains the shortcomings of each method.
E Only the second half of the passage discusses patterns in the occurrence of past earthquakes; the first half discusses a different method for predicting the occurrence of earthquakes.
The correct answer is D.

单选题 12.According to the passage, laboratory evidence concerning the effects of stress on rocks might help account for

【正确答案】 B

【答案解析】Supporting ideas
This question asks for information explicitly stated in the passage. The first paragraph explains that rocks subjected to stress in the laboratory undergo multiple changes. According to dilatancy theory, such changes happening to rocks in the field could lead to earthquake precursors— phenomena that occur before large earthquakes.
A The passage explains how laboratory evidence might be used to predict the occurrence of large earthquakes, not to differentiate between earthquakes' magnitudes.
B Correct. According to dilatancy theory, the sort of changes that have been observed in laboratories to occur in rocks might lead to earthquake precursors in the field.
C Although the passage discusses variation in earthquake intervals, that evidence is based on historical records, not laboratory evidence.
D The passage does not refer in any way to differences in the frequency of earthquakes in various regions.
E The unreliability of one method for making short-term earthquake predictions is implied by information gathered in the field, not by laboratory evidence.
The correct answer is B.

单选题 13.It can be inferred from the passage that one problem with using precursory phenomena to predict earthquakes is that minor tremors

【正确答案】 E

【答案解析】Inference
This question asks what can be inferred from certain information in the passage. The second paragraph explains two problems with using minor tremors to predict earthquakes. First, minor tremors provide no information about how large an impending earthquake will be. Second, the minor tremors that occur prior to a large earthquake are indistinguishable from other minor tremors. Thus, it can be inferred that minor tremors sometimes occur when no large earthquake follows.
A The passage does not mention the distance between minor tremors and ensuing earthquakes.
B The passage implies that minor tremors sometimes occur without an ensuing earthquake, so the phenomena are most likely not directly linked.
C The passage suggests no difficulty in distinguishing between minor tremors and major tremors.
D The passage does not mention any difficulties in the measurement of minor tremors.
E Correct. The passage indicates that minor tremors occurring prior to a large earthquake are indistinguishable from minor tremors that are not followed by large earthquakes. So the fact that minor tremors are not always followed by large earthquakes, together with the inability to distinguish between those that are and those that are not, poses a problem for a ny attempt to predict large earthquakes on the basis of this type of precursory phenomena.
The correct answer is E.

单选题 14.According to the passage, some researchers based their research about long-term earthquake prediction on which of the following facts?

A、 The historical record confirms that most earthquakes have been preceded by minor tremors.
B、 The average interval between earthquakes in one region of the San Andreas Fault is 132 years.
C、 Some regions tend to be the site of numerous earthquakes over the course of many years.
D、 Changes in the volume of rock can occur as a result of building stress and can lead to the weakening of rock.
E、 Paleoseismologists have been able to unearth and date geological features caused by past earthquakes.

【正确答案】 C

【答案解析】Supporting idea
This question asks for information explicitly provided in the passage.The question asks what the basis is for the research into long-term earthquake prediction described in the third paragraph. Based on the fact that numerous earthquakes occur in some regions over the course of many years, the researchers tried to identify regular earthquake intervals that would assist in making long-term predictions. Thus, the basis of their research is the occurrence of numero is earthquakes at particular sites.
A The passage indicates that minor tremors are used by some scientists to make short-term earthquake predictions, not that they were the basis for research about long-term predictions.
B This fact about the San Andreas Fault was used by paleoseismologists to show the inadequacy of the long-term prediction research, since actual earthquake intervals varied greatly from the average.
C Correct. Since earthquakes occur repeatedly in certain regions, researchers tried to identify regular cycles in earthquake intervals.
D The passage indicates that changes in rock volume have been used by some scientists to make short-term earthquake predictions, not that they were the basis for research about long-term predictions.
E Paleoseismologists' research provided evidence against the existence of regular earthquake cycles used in making long-term predictions.
The correct answer is C.

单选题 15.The passage suggests which of the following about the paleoseismologists' findings described in lines 42-50?

A、 They suggest that the frequency with which earthquakes occurred at a particular site decreased significantly over the past two millennia.
B、 They suggest that paleoseismologists may someday be able to make reasonably accurate long-term earthquake predictions.
C、 They suggest that researchers may someday be able to determine which past occurrences of minor tremors were actually followed by large earthquakes.
D、 They suggest that the recurrence of earthquakes in earthquake-prone sites is too irregular to serve as a basis for earthquake prediction.
E、 They indicate that researchers attempting to develop long-term methods of earthquake prediction have overlooked important evidence concerning the causes of earthquakes.

【正确答案】 D

【答案解析】Inference
This question asks about what can be inferred from a particular portion of the passage (lines 42-50). The third paragraph describes research that attempted to identify regular patterns of recurrence in earthquake-prone regions, to aid in long-term earthquake prediction. The fourth paragraph describes evidence discovered by paleoseismologists that undermines this idea that regular earthquake cycles exist. The paragraph indicates that in one region along the San Andreas Fault, the average interval between earthquakes was 132 years, but individual intervals varied widely—from 44 to 332 years. This information implies that earthquake intervals are too irregular to be used for accurate long-term earthquake prediction.
A The evidence suggests that the earthquake intervals are irregular, not that they have become shorter over time.
B The findings provide evidence against the use of regular earthquake cycles in long-term earthquake prediction.
C The findings do not clearly pertain to minor tremors.
D Correct. The great variation in intervals between earthquakes suggests that recurrence is too irregular to serve as the basis for long-term earthquake prediction.
E The paleoseismologists studied evidence showing when earthquakes occurred. The passage does not suggest that the evidence has any implications regarding the causes of earthquakes.
The correct answer is D.

单选题 16.The author implies which of the following about the ability of the researchers mentioned in line 18 to predict earthquakes?

A、 They can identify when an earthquake is likely to occur but not how large it will be.
B、 They can identify the regions where earthquakes are likely to occur but not when they will occur.
C、 They are unable to determine either the time or the place that earthquakes are likely to occur.
D、 They are likely to be more accurate at short-term earthquake prediction than at long-term earthquake prediction.
E、 They can determine the regions where earthquakes have occurred in the past but not the regions where they are likely to occur in the future.

【正确答案】 C

【答案解析】Supporting idea
The question asks for information explicitly provided in the passage. The second paragraph indicates that researchers at first reported success in identifying earthquake precursors, but further analysis of the data undermined their theory. The passage then explains that atypical seismic waves were recorded before some earthquakes; this evidence at first seemed to support the researchers' theory, before further analysis proved the evidence inadequate.
A Although earthquakes are caused by stress on rock, the passage does not indicate that this fact encouraged researchers to believe that precursors could be used to predict earthquakes.
B This fact would undermine the theory that changes in seismic waves are precursory phenomena that can be used to predict earthquakes.
C Correct. Seismic waves with unusual velocities occurring before earthquakes at first seemed to provide support for researchers' theory that earthquakes could be predicted by precursory phenomena.
D Though earthquakes' recurrence in certain regions is mentioned as being important to researchers seeking to make long-term earthquake predictions, it is not mentioned as being relevant to researchers' theory that earthquakes can be predicted by precursory phenomena.
E This is not mentioned as being relevant to scientists' belief that earthquakes could be predicted on the basis of precursory phenomena.
The correct answer is C.