为了帮助同学们顺利进行tpo42听力答案Lecture2。
Lecture 2(Astronomy)
QUESTIONS
1. What is the main purpose of the lecture?
A. To explain the difficulty of classifying distant objects in the universe
B. To introduce a classification system for galaxy clusters
C. To present some recent discoveries about the shapes of galaxies
D. To describe some differences between galaxies and clusters
答案：B
解析：根据原文第一二句话，“Before we continue talking about the properties of individual galaxies, it’s worth talking about the distribution of galaxies in space. Efforts at mapping or survey in the universe, making it sort of atlas of galaxies have been going on more than fifty years. ”可知，教授在本节课中将会对星系团的分布及类别进行讲解。所以B选项正确。
2. What did Shapley and Ames discover about the universe?
A. Most galaxies are symmetrical.
B. More galaxies exist in the universe than was once believed.
C. Galaxies occur in clusters throughout the universe.
D. Clusters are distributed uniformly throughout the universe.
答案：C
解析：根据原文 “And they made an important discovery. Their survey was the first to indicate that the galaxies were not distributed uniformly in space, some areas have a lot of galaxies, and the other areas had just a few. Another way to put in this is just say that galaxies are clustered. They are not spread evenly in the universe. So we have stars group together in galaxies and in galaxies group together in cluster.” 可知Shapley和Ames的发现就是星系是成群分布的，所以C选项正确。
3. Why does the professor emphasize the number of clusters mapped by Abell?
A. To help explain why Abell’s classification scheme was widely adopted
B. To explain why Abell was the first astronomer to notice spiral-shaped galaxies
C. To provide evidence that Abell’s method of surveying galaxies was superior to that used for previous surveys
D. To show how much Abell relied on earlier research
答案：A
解析：根据关键词classification scheme定位至原文 “One of the reasons his scheme has been so widely accepted is because his sample size. With all the clusters in his sample, he could determine the different characteristics of clusters and these characteristics form the basis of his classification scheme” 可知A选项为同义替换，所以A选项正确。
4. What aspects of clusters did Abell use to classify them?
Click on 2 answers.
A. The density of the cluster
B. The shape of the cluster
C. The age of the cluster
D. The type of galaxies in the cluster
答案：A, B
解析：根据原文“Now, two of the characteristics crucial to his classification were richness and symmetry. ”
根据原文学生提问 Is that the same as density? 教授回答：That’s right, both richness and density refer to the number per area. 所以A选项正确。
根据原文学生提问And symmetry just refers to its shape? 教授回答：Graphically speaking yes. 所以B选项正确。
5. Why does the professor discuss the Coma and Virgo clusters?
A. To indicate a limitation of Abell’s survey
B. To distinguish between rich and non-rich clusters
C. To demonstrate that clusters considered irregular in shape are basically spherical
D. To illustrate that the shape of a cluster is independent of the shape of the galaxies within it
答案：D
解析：根据原文 “But the individual galaxies within it are elliptical. They are not spherical or spiral shaped. ”可知星系团的形状和其中星系的形状是独立的。所以D选项正确。
6. What is the professor's opinion of Abell's assumption that all clusters are about the same size?
A. He is surprised that it has been disproved.
B. He believes that there is not enough data to support it.
C. He is impressed that it has been proved correct.
D. He thinks it is Abell’s most important contribution to astronomy.
答案：C
解析：根据原文 “And it was just an assumption that all clusters to about the same size. It’s remarkable that it proved to be correct. ” 所以C选项正确。