11.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.
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？
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？