地质学 TPO49-L1 Permafrost and thaw lakes in Alaska

地质学

TPO49-L1 Permafrost and thaw lakes in Alaska

Listen to part of a lecture in a geology class.

 



  1. What is the main purpose of the lecture?
    [CHOOSE 2 ANSWERS]
  • A. To contrast how different kinds of thaw lakes grow
  • B. To explain why a new theory of thaw lakes is gaining acceptance
  • C. To explain how processes in permafrost lead to the formation of thaw lakes
  • D. To describe two competing theories about the growth of thaw lakes
  1. The professor explains thaw lake formation as a cycle of events that occur repeatedly.
    [Summarize this cycle, and put them in order.]
  • A.Meltwater flows into cracks in permafrost
  • B.Ice wedges inside permafrost completely melt
  • C.Freezing water expands cracks in permafrost
  • D.Ice in the active layer melts as temperatures rise
  • E.Permafrost shrinks and cracks as temperatures drop
  1. What is the significance of the “protective shelf” discussed by the professor?
  • A. It prevents the slumping of lake banks.
  • B. It shields the lake surface from strong winds.
  • C. It redirects the waves to lake banks that do not face the wind.
  • D. It allows the lakes to grow in the same direction as the wind blows.
  1. According to the thaw slumping model, which side of a thaw lake grows fastest?
  • A. The side where the bank is shortest
  • B. The side least exposed to wind
  • C. The side that is at the highest elevation
  • D. The side opposite the protective shelf
  1. What is the professor’s opinion of the thaw slumping model?
  • A. He thinks it was urgently needed.
  • B. He is not convinced that it has a firm basis.
  • C. He thinks it would be better if it were simplified.
  • D. He does not think it is very different from the old model.
  1. Why does the professor say this: 🎧

 

  • A. He wants some information from the students.
  • B. He thinks that the students may find an example helpful.
  • C. He realizes that he forgot to mention an important topic.
  • D. He wants to point out an important difference between frozen ground and dry ground.



答案:
CD EDACB C A B B


发表评论

电子邮件地址不会被公开。 必填项已用*标注