GRE阅读练习每日一篇(五十二)_GRE阅读

GRE阅读练习每日一篇(五十二)

　　Provided evidence that many observations are actually hallucinations.

　　Explained why new observations often invalidate preexisting generalizations.

　　Challenged the mechanism by which specific generalizations are derived from collections of particular observations.

　　Mentioned other critics of classical empiricism and the substance of their approaches.

　　Gave an example of a specific generalization that has not been invalidated despite a contrary observation.

　　20. It can be inferred from the passage that Quine considers classical empiricism to be overly narrow for which of the following reasons?

　　I. Classical empiricism requires that our system of generalizations be free of contradictions.

　　II. Classical empiricism demands that in the case of a contradiction between an individual observation and a generalization, the generalization must be abandoned.

　　III. Classical empiricism asserts that every observation will either confirm an existing generalization or initiate a new generalization.

　　II only

　　I and II only

　　I and III only

　　II and III only

　　I, II, and III

　　Until recently astronomers have been puzzled by the fate of red giant and supergiant stars. When the core of a giant star whose mass surpasses 1.4 times the present mass of our Sun exhausts its nuclear fuel, it is unable to support its own weight and collapses into a tiny neutron star . The gravitational energy released during this implosion of the core blows off the remainder of the star in a gigantic explosion, or a supernova. Since around 50 percent of all stars are believed to begin their lives with masses greater than 1.4M⊙, we might expect that one out of every two stars would die as a supernova. But in fact, only one star in thirty dies such a violent death. The rest expire much more peacefully as planetary nebulas. Apparently most massive stars manage to lose sufficient material that their masses drop below the critical value of 1.4 M⊙ before they exhaust their nuclear fuel.