propose a modification in the most widely accepted theory of spiral-galaxy structure
compare and contrast the roles of clouds of gas and dust in two theories of spiral-galaxy structure
describe a new theory of spiral-galaxy structure and contrast it with the most widely accepted theory
describe a new theory of spiral-galaxy structure and discuss a reason why it is inferior to the most widely accepted theory
18. The passage implies that, according to the new theory of spiral-galaxy structure, a spiral galaxy can be created by supernovas when the supernovas are
producing an underlying density wave
affected by a density wave of spiral form
distributed in a spiral pattern
located in the central plane of a galaxy
located in a differentially rotating galaxy
19. Which of the following, if true, would most discredit the new theory as described in the passage?
The exact mechanism by which a star becomes a supernova is not yet completely known and may even differ for different stars.
Chains of star-forming regions like those postulated in the new theory have been observed in the vicinity of dense clouds of gas and dust.
The most massive stars formed from supernova explosions are unlikely to evolve into supernovas.
【gre阅读练习每日一篇(三十六)】相关文章:
最新
2016-03-01
2016-03-01
2016-03-01
2016-03-01
2016-03-01
2016-03-01