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Scientists had expected the Sun’s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan’s surface. But Cassini detected no acetylene on the surface.
The absence of detectable acetylene on the Titan’s surface can very well have a non-biological explanation,said Mark Allen,a principal investigator of the NASA Titan team.
“Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,”Allen said. “We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process,without biology,can explain these results.”
36 .What have scientists found about Saturn?
A .They have found a new moon orbiting Saturn.
B. They have found methane-based life on Saturn.
C. They have found methane-based life on Titan.
D. They have found earthlike life on a Saturn’s moon.
37. What do scientists say about Titan?
A. There are life clues there.
B. There is acetylene there.
C. Water on Titan exists in the form of ice.
D. Rivers and lakes there contain life formls.
38. To date, scientists have not yet detected this form of life. (paragraph 5) What does “this form of life” refer to?
A. Water-based life.
B. Methane-based life.
C. Liquid-water-based microorganisms.
D. Gas-based life.
39. What can be inferred from what Allen said?
A. Scientists have different arguments over whether there is life on Titan.
B. Scientists all agree that there is life on Titan.
C. Scientists all suggest that a biological explanation is reasonable.
D. Scientists all agree that a non-biological chemical reaction is a possible explanation.
40. Which of the following can replace the title of this passage?
A. Earthlike Living Beings Found on Titan.
B. Finding of One More Moon of Saturn.
C. Titan,a New Satellite Found.
D. A different Life Form, a Possibility.
Listening Device Provides Landslide Early Warning
A device that provides early warningof a landslide by monitoring vibrations in soil is being testedby UK researchers. The device dould save thousands of lives each year by warning when an area should be evacuated, the scientists say. Such natural disasters are common in countries that experience sudden, heavy rainfall, and can also be triggered by earthequakes and even water erosion.
Landslides start when a few particles of soil or rock within a slope start to move,but the early stages can be hard to spot. Following this initial movement,"slopes can become unstable in a matter of hours or minutes," says Nell Kixon at Loughborough university, UK. He says a warning system that monitors this movement “might be enough to evacuate a block of flats or clear a road, and save lives.”