Scientists have found what look like caves on Mars(火星), and say they could be protecting life from the planet’s terrible environment.
The first caves discovered beyond the Earth appear as seven mysterious black dots on the pictures sent back by NASA’s Mars Odyssey orbiter. Each as large as a football field, they may be openings into natural caves below the Martian surface.
“If there is life on Mars, there is a good chance you’d find it in caves,” said Jut Wynne, one of the researchers who noticed the features while working on a US Geological Survey Mars Cave Detection Program.
Jonathan Clarke, a geologist with the Mars Society of Australia, yesterday described the discovery as exciting.
One photo taken at night by an infrared imager(红外线成像器) showed one hole to be unusually warm, suggesting hot air trapped during the day is flowing out.
“I said: ‘Wow, that’s a cave’” Dr. Clarke said excitedly. “People have been looking for these for a long time; now we have found them.”
He agreed such caves would be perfect places to hunt for life escaping from the bitterly cold, radiation-soaked(充满辐射的), dry surface.
“Tiny drops of water could collect inside,” he said. “If there are gases ing out, they could provide energy for a whole range of bacteria. A cave is also a protection from radiation; the surface of Mars is exposed to high levels of space radiation.”
The caves probably formed when tube-shaped lave flows(管状岩浆流) spread across the planet long ago. The outside of the tubes cooled, forming solid walls, while something hotter inside allowed the remaining have to flow out, forming caves.
【小题1】What does the passage mainly talk about?A．How the caves were formed on Mars.B．How scientists found these caves on Mars.C．Caves on Mars may be full of hot air or a sign of life.D．Scientists have pletely recognized the surface of Mars.【小题2】We can learn from the passage that .A．water has already been found on MarsB．the scientists found all the caves at nightC．it is certain that there is life in these cavesD．the surface of Mars is bitterly cold, radiation-soaked and dry【小题3】According to the passage, Dr. Clarke was so excited because .A．such caves could provide energy for lifeB．they had finally found the caves on MarsC．such caves would be perfect places to hunt for lifeD．scientists had long been looking for these caves【小题4】Necessary conditions for life on Mars mentioned in the passage may include .A．lava and energyB．water and radiation from spaceC．gases and lavaD．water and protection from radiationC
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(答案→)C
解析：
【小题1】这是一道主旨题。本文主要介绍了科学家在火星上发现一些坑洞，这些坑洞可以聚集热空气和水分，使生命出现变得可能。本文也描述了这些坑洞发现的过程和形成原因，但都不是主要描述的内容，所以A项和B项不全面。
【小题2】这是一道判断题。根据倒数第三段“He agreed such caves would be perfect places to hunt for life escaping from the bitterly cold, radiation-soaked, dry surface.”可以判断出火星表面是个极端寒冷、充满辐射、干燥的地方。A、C选项都是文中的推测，并没有得出明确的结论。
【小题3】这是一道推断题。根据第六段Dr.Clarke的表述“People have been looking for these for a long time；now we have found them.”可知Clarke教授的喜悦是因为人们找这些坑洞很长时间了，现在终于找到了。
【小题4】这是一道归纳题。根据坑洞中可能出现生命以及倒数第二段“Tiny drops of water could collect inside,”和“A cave is also a protection from radiation”可以归纳出生命产生需要水和避免辐射。