听力音频：
L1
讲座
1. What is the lecture mainly about?
Interactions between methane and water in the Martian atmosphere
A technological breakthrough that led to the discovery of an unusual type of methane on Mars
Issues that have been raised by the discovery of methane in the atmosphere of Mars D.
The theory that life on Mars evolved from organisms that survive on methane gas alone
2. Why does the professor mention isotopes?
To describe how the source of methane is determined
To explain how astronomers know that liquid water once existed on Mars
To offer an explanation for the fluctuations of methane levels in the soil on Mars
To point out the importance of studying chemistry along with astronomy
3. According to the professor,what is unusual about the methane that has been found on Mars?
It has characteristics of both biological and nonbiological methane
It is not broken down by ultraviolet radiation from the Sun.
It has a lower atomic weight than the methane in Earth’s atmosphere.
It remains in the Martian atmosphere for only a short time.
4. What is the professor’s opinion about the proposed research to investigate methane on Mars using satellites or balloons?
He suspects that the low methane concentrations on Mars will make the research difficult
He does not think that the research will answer the question he considers most important.
He believes that the proposed research could lead to surprising conclusions.
He is excited about the new technologies that the research would involve.
5. What does the professor imply about deposits of clay minerals beneath the surface of Mars?
They are a possible source of nonbiological methane on Mars.
They are evidence that life could have existed on Mars
They could help explain the low amounts of methane on Mars
They indicate that it is unlikely that large amounts of water ever existed on Mars
6. What area of research does the professor say is promising?
Devising new methods to obtain methane samples from Mars
Verifying the presence of methane on other planets in the solar system
Looking in space for additional chemicals that could be the result of biological processes
Comparing methane found on Earth with methane samples from Mars
