GRE模拟题：自测试题二（4）

　　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.

　　12.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 deprivation?

　　(E)Is the incidence of sleep deprivation higher among physicians than it is among other health care workers?