{{I}} Questions 7 to 10 are based on the
following conversation. At the end of the conversation, you will be given 20
seconds to answer the questions. Now listen to the
conversation.{{/I}}
单选题
What are speakers mainly discussing?
【正确答案】
C
【答案解析】[听力原文]7-10
M: How did you like yesterday's astronomy class?
W: It was interesting. But the point she was trying to make seemed a little far-fetched.
M: Oh, that new theory that ocean water came from comets?
W: Yeah. Do you remember what it was based on?
M: Some recent satellite photos, I think. Apparently, space satellites recently detected thousands of small comets colliding with earth's outer atmosphere, almost 40,000 per day.
W: Ok, so they collided with the atmosphere. So that's what created the water?
M: It's not that the collision created water. Comets contain water. They are made up mostly of cosmic dust and water. When they collide with the atmosphere, they break up. And the water they contain rains down to earth. Ocean water came from that rain.
W: Oh. Well, this morning I asked my geology professor about that. He said that most geologists draft accept it.
M: Why not?
W: Their research indicates that most of the water molecules from the comet would have burned up as they fell through the atmosphere. Enough rain couldn't have reached the earth to fill up the ocean.
M: Well, did the geologists have an alternative theory to explain where ocean water came from?
W: Yeah, he said the more traditional view is that the ocean water came from volcanoes.
M: From volcanoes?
W: Right. They say volcanic fumes are mostly steam. And they claimed that it was the volcanic steam that created the oceans, not rain from comets.
本题考查内容大意。根据原文可知两人谈沦的是昨天的天文学课上学到的对海洋来源的最新的研究成果，重点讨论的是地球上水的来源。因此选项 C为正确答案。
单选题
What did recent photographs from a space satellite indicate?
【正确答案】
D
【答案解析】本题考查事实。根据原文“Apparently, space satellites recently detected thousands of small comets colliding with earth's outer atmosphere, almost 40, 000 per day.”可知每天大约有40,000个小彗星与地球的外气层相碰撞。因此选项 D为正确答案。
单选题
According to the new theory, where did ocean water come from?
【正确答案】
A
【答案解析】本题考查事实。根据原文“Comets contain water.”及后面提到的“When they collide with the atmosphere, they break up. And the water they contain rains down to earth. Ocean water came from that rain.”可知当彗星与地球外气层相碰撞时，彗星中包含的水分会落到地球上来。因此选项A为正确答案。
单选题
What group disagrees with the new theory described in the conversation?
【正确答案】
B
【答案解析】本题考查事实。根据原文“Well, did the geologists have an alternative theory to explain where ocean water came from?”和随后的回答“Yeah, he said the more traditional view is that the ocean water came from volcanoes.”可以得知他的地理学教授说大部分地理学家不赞成这一说法。因此选项B为正确答案。