9.The early universe contained only the lightest elements， hydrogen and helium. Heavier elements，such as carbon， form only in nuclear reactions in stars and are dispersed when the stars explode. A recently discovered gas cloud contained carbon several billion years ago， when the universe was no more than two billion years old.
If the statements above are true， which of the following must， on the basis of them， also be true?
(A)The earliest stars contained only hydrogen.
(B)Some stars were formed before the universe was two billion years old.
(C)The carbon in the gas cloud later formed part of some stars.
(D)No stars identified to date are as old as the gas cloud.
(E)The gas cloud also contained hydrogen and helium.
10.Sleep deprivation is a known cause of workplace error， and many physicians frequently go without sleep for periods of 24 hours or more. However， few of these physicians have， in the course of a routine examination by a peer， been diagnosed with sleep deprivation.So there is little cause for concern that habitual sleep deprivation will cause widespread physician error.
The answer to which of the following questions would be most helpful in evaluating the argument?
(A)Do physicians who have been diagnosed with sleep disorders also show signs of other ills not related to sleep deprivation?
(B)Is the ability to recognize the symptoms of sleep deprivation in others significantly impaired by habitual sleep deprivation?
(C)Do factors other than habitual sleep deprivation ever lead to errors in the workplace on the part of physicians?
(D)Of people who have recently been treated by physicians， what percentage believe that many physicians have occasionally suffered from sleep
(E)Is the incidence of sleep deprivation higher among physicians than it is among other health care workers?
11.A list of the fifteen operas most frequently performed in recent times includes no works by the nineteenth-century German composer Richard Wagner. Although music producers tend to produce what audiences want，relative infrequency of performance probably does not indicate lack of popularity in Wagner's case， since Wagner's operas are notoriously expensive to perform on stage.
Which of the following， if true， most strongly supports the conclusion of the argument above?
(A)The list of most frequently performed operas does not include operas produced by small amateur groups.
(B)Some opera companies are backed by patrons who are willing to commit large sums of money in order to enjoy lavish productions.
(C)All of the fifteen most frequently performed operas of recent times are works that have been popular for at least 75 years.
(D)More recordings have been produced recently of the works of Wagner than of the works of any other composer of opera.
(E)Operatic works of all kinds have been increasing in popularity in recent years.
12.The bodies of dwarf individuals of mammalian species are generally smaller in relation to those of nondwarf individuals than are the teeth of the dwarf individuals in relation to those of the nondwarf indi- viduals. Fragmentary skeletal remains of an adult dwarf woolly mammoth were recently found. The teeth are three-fourths the size of the teeth of an average adult nondwarf woolly mammoth.
The statements above， if true， most strongly support which of the following?
(A)The body of the dwarf woolly mammoth was less than three-fourths the size of the body of an average adult nondwarf woolly mammoth.
(B)None of the teeth of the dwarf woolly mammoth that were recently discovered was as large as any of the teeth of nondwarf woolly mammoths that have been discovered.
(C)The teeth of most adult dwarf individuals of mammalian species are three- fourths the size of the teeth of the adult nondwarf individuals of the same species.
(D)Dwarf woolly mammoths had the same number of teeth as did nondwarf woolly mammoths.
(E)Dwarf individuals of most mammalian species are generally no more than three-fourths the size of the adult nondwarf individuals of those species.
13.Excluding purchases by businesses， the average amount spent on a factory-new car has risen 30 per-cent in the last five years. In the average household budget， the proportion spent on car purchases has remained unchanged in that period. Therefore the average household budget must have increased by 30 percent over the last five years.
Which of the following is an assumption on which the argument relies?
(A)The average number of factory-new cars pur-chased per household has remained unchanged over the last five years.
(B)The average amount spent per car by businesses buying factory-new cars has risen 30 percent in the last five years.
(C)The proportion of the average household budget spent on all car-related expenses has remained unchanged over the last five years.
(D)The proportion of the average household budget spent on food and housing has remained unchanged over the last five years.
(E)The total amount spent nationwide on factory-new cars has increased by 30 percent over the last five years
参考答案： 9.B 10.B 11.D 12.A 13.A