单项选择题

Which of the following, if true, would cast most doubt on the conclusions drawn from Head's higher-resolution models

A． The results of geographical survey prove that no crater larger than twelve kilometers exists on the surface of Mars.
B． Fragments from smaller impact events on Mars are highly unlikely to survive entry through the Earth's atmosphere.
C． The velocity of rocks escaping from Mat's gravity is greater when they have been loosened by a large impact.
D． Huge impacts on Mars are proven to be less rare than was previously thought.
E． A double-succession of large impacts is found to have occurred on Mars in a relatively short period of time.

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单项选择题

The passage suggests that which of the following is true concerning the probability that a given collision on Mars would eject fragments that will hit the Earth

A． The probability is higher if the impact produces a crater larger than three kilometers.
B． The probability is lower if the impact produces a crater smaller than three kilometers.
C． The probability is decreased when the impact comes from an area of Mars covered by debris.
D． The probability is decreased when the fragments produced by the impact are larger than 10 centimeters.
E． The probability is decreased when the fragments produced by the impact are younger.

单项选择题

With which of the following statements concerning the condition of the Anasazi at the time of their evacuation would the author be most likely agree

A． Disruption of weather patterns is a plausible explanation of the Anasazi's evacuation, but insufficient when taken individually.
B． A religious crisis may have contributed to lower crop fertility, resulting in the Anasazi's malnourishment.
C． The Anasazi spiritual crisis may have been exacerbated by the poor performance of their crops after the disruption of weather patterns.
D． The Anasazi may have been attempting to move toward a diversification of their religious beliefs long before the disruption of weather patterns.
E． The Anasazi spiritual crisis may have contributed to increased balkanization, creating a vicious cycle of hostility within Anasazi society.