[单项选择]According to the passage, scientists are skeptical toward their equations because scientists ______.


A. work to explain real, rather than theoretical or simplified situations
B. know that well-defined problems are often the most difficult to solve
C. are unable to express their data in terms of multiple variables
D. are unwilling to relax the axioms they have developed

[单项选择]According to the passage, scientists are skeptical toward their equations because scientists ______.


A. work to explain real, rather than theoretical or simplified situations
B. know that well-defined problems are often the most difficult to solve
C. are unable to express their data in terms of multiple variables
D. are unwilling to relax the axioms they have developed

[单项选择]According to passage, scientists failed to______.


A. discover the characteristic of nuclear process
B. discover the nature of uranium ore
C. save the life of uranium miners
D. store nuclear wastes in underwater tanks

[单项选择]According to the passage, scientists have decided that sulfur aerosols from volcanic eruptions affect global temperatures to a greater extent than ash clouds because


A. the greenhouse gas effect produced by human activities tends to have a much greater environmental effect than that of volcanic explosions
B. clouds of sulfur-rich gases tend to achieve greater heights in the stratosphere than do ash clouds
C. a particular explosion producing high sulfur and little ash had a greater environmental effect than the converse
D. the burning of fossil fuels tends to exacerbate the effects of sulfurous aerosols, but not those of ash clouds
E. (E) global warming effects tend to minimize the impact of ash clouds, but not those of sulfurous aerosols

[单项选择]According to tile passage, scientists used isotopes from the water of the ice core to determine which of following
A. ( The amount of air that had bubbled to the surface since the ice had formed
B. ( The temperature of the atmosphere when the ice was formed
C. ( The date at which water had become locked in the glacier
D. ( The rate at which water had been frozen in the glacier

[单项选择]According to the passage, scientists have positively confirmed that the brains of narcoleptics differ from those of normal brains in which of the following ways
A. (A) Narcoleptic brains tend to remove degenerative tissue at a more prolific rate than that of nonnarcoleptics.
B. (B) Narcoleptics are less responsive to drugs which treat neural autoimmune dysfunction than are nonnarcoleptics.
C. (C) Nonnarcoleptics do not possess the same neurological immune antigens as narcoleptics.
D. (D) Neurons that control muscle tone are damaged in the brains of narcoleptics, but not in those of non-narcoleptics.
E. (E) Narcoleptics experience greater neural degeneration as a result of aging than do nonnarcoleptics.

[单项选择]According to the passage, scientists cannot explain which of the following aspects of squirrel behavior
A. Where squirrels store their acorn caches
B. Why squirrels prefer acorns over other seeds
C. Why squirrels eat only a portion of each acorn they retrieve
D. Why squirrels prefer acorns from a particular species of oak trees

[单项选择]According the passage, the housework often brings satisfaction to women ______.
A. who are very rich
B. who envy their neighbors
C. who work outside the home
D. who are dependent on their husbands

[单项选择]According to passage, Indian names were important because they ______.
A. described the character of a man
B. described the appearance of a man
C. were never used by other people
D. told us his profession

[单项选择]According to passage, human beings can survive almost everywhere on Earth because ______.


A. they have developed advanced forms of transportation
B. they have learned how to process seawater for drinking
C. their body temperature can vary considerably
D. their shelters and clothing help them to adapt to the environment

[单项选择]According the passage we know that the two brothers ______.


A. got a large amount of money from their uncle
B. used to make a living by fishing and were quite rich
C. once lived in poverty
D. gave up the search for the sunken treasure after they had a try