17. The author focuses primarily on

　　(A)presenting two competing scientific theories concerning solar

　　activity and evaluating geological evidence often cited to support them

　　(B)giving a brief overview of some recent scientifrc developments

　　in s'olar physics and assessing their impact on future climatological research

　　(C)discussing the difficulties involved in linkinl： ter- restrial

　　phenomena with solar activity and indicating how resolving that issue

　　could have an impact on our understanding of solar physics

　　(D)pointing out the futility of a certain line of sci- entific inquiry

　　into the terrestrial effects of solar activity and recommendine ita

　　aban- donment in favor of purely physics-oriented research

　　(E)outlinine the specific reasons why a problem in solar physics has

　　not yet been solved and faulting the overly theoretical approach of modern

　　physicists.

　　18. Which of th.e following statements about the two models of solar

　　activity. as they are described in lines 37-55, is accurate?

　　(A)In both modgls cyclical solar activity is regarded as a long-lived

　　feature of the Sun, persisting with little change over billions of years.

　　(B)Tn both models the solar-activity cycle is hypothesized as being

　　dependent on the large-scale solar magnetic field.

　　(C)Tn one model the Sun's magnetic fieid is thought to play a role in causing solar activity, whereas in the other model it is not.

　　(D)In one model solar activity is presumed to be unrelated to terrestrial

　　phenomena. whereas in the other model solar activity is thought to have

　　observable effects on the Earth.

　　(E)In one model cycles of solar activity with peri- odicities longer than

　　a few decades are con- sidered to be impossible, whereas in the other model

　　such cycles are predicted.

　　19. According to the passage, late seventeenth- and early eighteenth-century Chinese records are important for which of the following reasons?

　　(A)They suggest that the data on which the Maunder minimum was predicated were incorrect.

　　(B)They syggest that the Maunder minimum can- not be related to climate.

　　(C)Thcy suggest that the Maunder minimum might be \-'alid only for Europe.

　　(D)They establish the existence of a span of unusu- ally cold weather worldwide at the time of the Maunder minimum.

　　(E)They establish that solar activity at the tirne of the Maunder minimum

　　did not significantly vary from its present pattern.

　　20. The author implies which of the followine about currently available geological and archaeoloeical evidence concerning the solar-activity cycle?

　　(A)It best supports the model of solar activity described in lines 37-45.

　　(B)It best supports the model of solar activity described in lines 45-52.

　　(C)It is insufficient to confirtn either model of solar activity described in the third paragraph.

　　(D)It contradicts both models of solar activity as they are presented in the third paragraph.

　　(E)It disproves the theory that terrestrial weather and solar activitv are linked in some way.

　　21. Tt can be inferred from the passage that the argu- ment in favor of the model described in lines 37- 45 would be strengthened if which of the following were found ta he tme?

　　(A)Episodes of intense volcanic eruptions in the distant past occurred in cycles having very long periodicities.

　　(B)At the present time the global level of thunder- storm activity increases and decreases in cycles with periodicities of approximately 11 years.

　　(C)In the distant past cyclical climatic changes had periodicities of longer than 200 years.

　　(D)In the last century the length of the sunspot cycle has been known to vary by as much as 2 years from its average periodicity of 11 years.

　　(E)Hundreds of millions of years ago, solar- activity cycles displayed the same periodicities as do present-day solap-activity cycles.

　　22. lt can be inferred from the passage that Chinese observations of the Sun during the late seventeenth and early eighteenth centuries

　　(A)are ambiguous because most sunspots cannot be seen with the naked eye

　　(B)probably were made under the same weather conditions as those made in Europe

　　(C)are more reliable than European observations . made during this period

　　(D)record some sunspot activity during this period

　　(E)have been employed by scientists seeking to argue that a change in solar activity occurred during this period.

　　23. It can be inferred from the passage that studies attempting to use tree-ring thickness to locate possi- ble links between solar periodicity and terrestrial climate are based on which of the following assump- tions?

　　(A)The solar-activity cycle existed in its present form during the time period in which the tree rings erew.

　　(B)The biological mechanisms causing tree growth are unaffected by short-term weather patterns.

　　(C)Average tree-ring thickness varies from species to species.

　　(D)Tree-ring thicknesses reflecr changes in terres- trial climate.

　　(E)Both terrestrial climate and the solar-activity cycle randomly af~ct tree-ring thickness.

　　The common belief of some linguists that each language is a perfect vehicle for the thoughts of the nation speaking it is in some ways the exact counterpart of the conviction of the Manchester school of economics that supply and demand will regulate everything for the(5) best. Just as economists were blind to the numerous cases in which the law of supply and demand left actual wants unsatisfied, so also many linguists are deaf to those instances in which the very nature of a ianguage calls forth misunderstandings in everyday conversation, (10) and in which, consequently, a word has to be modified or defined in order to present the idea intended by the speaker: "He took his stick, no, not John's, but his own." No language is perfec't, and if we admit this truth, we must also admit that it is not unreasonable to investi-(15) gate the relative merits of different languages or of different details in languages.

　　24. The primary purpose of the passage is to

　　(A)analyze an interesting feature of the English language

　　(B)refute a belief held by some linguists

　　(C)show that economic theory is relevant to linguistic study

　　(D)iilustrate the confusion that can result from the improper use of language

　　(E)suggest a way in which languages can be made more nearly perfect.

　　25. The misunderstanding presented by the author in lines 13-14 is similar to which of the following?

　　I. X uses the word "you" to refer to a group, but Y thinks that X is referring to one person only.

　　II. X mistakenly uses the word "anomaly" to refer to a typical example, but Y knows that "anomaly" means "exception".

　　III. X uses the word "bachelor" to mean "unmarried man: "but Y mistakenly thinks that bachelor means "unmarried woman."

　　(A)I only

　　(B)II only

　　(C)III only

　　(D)I and II only

　　(E)IIand IIIonly