A、They are found under the oceans. B、They were most active when Earth was first formed. C、Their emissions created the Earth’s at

M: How did you like yesterday’s astronomy class?
W: It was interesting, but the point she was trying to make seemed a little farfetched.
M: Oh, that new theory that ocean water came from comets.
W: Yeah. Do you remember what it’s 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 collide 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 most geologists don’t accept it.
M: Why not?
W: Well, their researches indicate that most of the water molecules from the comets will have burn up as they fell through the’ atmosphere. Enough rain couldn’t have reached the earth to fill up the ocean.
M: Well, do the geologists have an alternative theory to explain where ocean water came from?
W: Yeah, he said the most traditional view is that ocean water came from volcanoes.
M: From volcanoes?
W: Right! As the volcanic fumes are mostly steam. And they claim that it was volcanical steam that create the oceans, not rain from comets.
Q. 11. What are the speakers mainly discussing?
Q. 12.What did recent photographs from a space satellite indicate?
Q. 13.According to the new theory, where did ocean water come from?
Q. 14.What aspect of volcanoes do the geologists mention?