50. Although the prevailing supposition has been that it is too hot for microorganisms to survive deep below the Earth's surface， some scientists argue that there are living communities of microorganisms there that have been cut off from surface life for millions of years.These scientists base their argument on the discovery of living microorganisms in samples of material that were taken from holes drilled as deep as 1.74 miles.
The scientists' argument depends on which of the fol-lowing assumptions?
(A)The microorganisms brought up were of a species that is related to those previously known to science.
(B)No holes have been drilled into the Earth's surface to a distance deeper than 1.74 miles
(C)The microorganisms did not come from surface soil that came into contact with the drilling equipment.
(D) The stratum from which the samples came has been below the surface of the Earth ever since the Earth came into existence.
(E) The temperature at the bottom of the holes drilled was not significantly hotter than that of the hottest spots on the Earth's surface.
51. For 20 years all applicants for jobs as technicians at EquipCorp were required to demonstrate that they could operate and repair the machinery that was central to EquipCorp's manufacturing business. Now， however，that particular machinery is obsolete， and very different machinery fills the central role. Therefore， the old requirement is no longer a useful method for evaluating whether applicants for jobs as technicians at EquipCorp have the skills necessary for the job.
Which of the following， if true， most strengthens the argument?
(A) The machinery that is now obsolete was used by a large number of manufacturing companies before it became obsolete.
(B) Among the people already holding jobs as tech-nicians at Equip Corp， those who are most skillful at operating the new machinery had been some of the least skillful at operating the old machinery
(C) Most people applying for jobs as technicians today have much broader skills than did people applying for jobs as technicians 20 years ago.
(D) The skills required to operate and repair the obsolete machinery are useful in operating and maintaining many other types of machinery at EquipCorp that are not obsolete.
(E) Much of the machinery that EquipCorp now uses in manufacturing is very likely to become obsolete within the next 20 years.
52. The university's constitution defines the powers of two governing bodies.The general council， which currently retains authority over constitutional matters， consists of all the university's living alumni.The twenty-member senate decides routine matters by majority vote.A new proposal suggests making a unanimous vote in the senate sufficient to change the constitution.
If the statements above are true， which of the following must follow on the basis of them?
(A) The proposal will take effect only if it receives the senate's unanimous support.
(B) Currently each member of the senate has power of veto over any proposal that comes before that body.
(C) Adopting the proposal would allow passage of constitutional changes without the general council's approval.
(D) Any of the university's alumni can fill any one of the twenty seats on the senate.
(E) Adopting the new proposal would increase the voice of the alumni in the conduct of university affairs.
53. Comparison of the growth rings of ancient trees enables scientists to determine from a piece of timber the year in which the tree used for the timber was felled.Hence， by analyzing the growth rings in timber surviving from ancient buildings， archaeolo gists can determine precisely when those buildings were constructed.
Which of the following is an assumption on which the argument depends?
(A) The timber used for construction purposes in ancient times was made from very old trees.
(B) The timber that was used in ancient building construction had not， prior to being used in the construction of the buildings， lain unused for an indeterminable amount of time.
(C) The growth rings of any tree felled in a given year are identical to the growth rings of any other tree felled in that year.
(D) The oldest of the ancient buildings that survive to the present day were constructed of the most durable woods.
(E) Ancient builders did not use more than one type of wood for the construction of a given building.
54. Color-tinting of movies originally photographed in black-and-white is inappropriate.Hundreds of the original artistic choices would have been made differently had these movies been filmed in color.Lighting on the sets of these movies was arranged to make highlights and shadows look right in black-and-white.
Which of the following claims， if substituted for the claim about the lighting of movie sets， would lend the same type of support to the argument above?
(A) An important part of what gives these movies their identity is the result of the black-and-white format.
(B) Color film would have better captured the film-makers' intentions.
(C) Color film is superior to black-and-white film for making movies.
(D) Makeup for the actors was applied so as to look best in black-and-white films.
(E) The choice of black-and-white film over color film is entirely a matter of taste.
参考答案： 50.C 51.B 52.C 53.B 54.D