Question

    The United States space agency, NASA. says its Mars exploration vehicle recently recorded a high level of methane (甲烷) gas on the planet. The discovery is exciting because the presence of methane gas could support the case for life on Mars.

NASA's Curiosity vehicle recently recoded the largest level of methane ever measured during its seven-year Mars mission.

Methane has no color or smell. A special instrument on Curiosity's Man Science Laboratory recorded the increased gas level. The device measures levels of chemical elements and gases in the Marian atmosphere. In addition to methane, the instrument can record levels of water and carbon dioxide.

Nearly all the methane gas found in Earth's atmosphere is produced by living thing. It usually comes from animal and plant life. But it can also be formed by geological(地质的) processes, such as interactions. between rocks and water.

It was not the first time Curiosity had found methane gas in the Martian atmosphere. About a year ago, NASA announced that Curiosity had discovered sharp seasonal increases in the gas. This time, NASA said the measured methane gas level was clearly larger than any others observed in the past. "It's exciting because microbial (微生物的) life is an important source of methane on Earth," NASA said in a statement announcing the discovery.

However, Curiosity's team carried out a follow-up methane experiment that showed a sharp drop in levels of the gas. That number was "close to the background levels Curiosity sees all the time." NASA said. The rise and fall of the methane gas levels left NASA scientists with more questions than answers.

"The methane mystery continues," said Ashwin Vasavada. Curiosity's project scientist, "We're more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Marian atmosphere."

1.What do we know about methane go?

A.It is a must to living things. B.It can be found everywhere.

C.It smells like carbon dioxide. D.It's mainly from biological activity.

2.What do the explorations on Mans tell us?

A.Humans have known much about Mars.

B.There will be more methane gas on Mars.

C.There is no progress in the 7 year's research.

D.The level of methane gas on Mars is not stable.

3.What does the discovery mean in NASA's view?

A.There may exist life on Mars.

B.Methane gas on Mars has a sudden increase.

C.The mystery about Mars will be solved soon.

D.They're known how methane as is formed on Mans.

4.How do the NASA's scientists feel about their future exploration?

A.Aimless. B.Confident.

C.Stressed. D.Serious.

Answer

1.D

2.D

3.A

4.B

【解析】

这是一篇科普说明文。美国宇航局，NASA，称其火星探测车最近在火星上记录到高水平的甲烷气体。这一发现令人兴奋，因为甲烷气体的存在可能支持火星上存在生命的说法。

1.推理判断题。根据第三段中Nearly all the methane gas found in Earth's atmosphere is produced by living thing. It usually comes from animal and plant life.“地球大气中几乎所有的甲烷气体都是由生物产生的。它通常来自于动物和植物。”由此可知，沼气主要来自生物活动。故选D。

2.推理判断题。根据倒数第二段最后一句The rise and fall of the methane gas levels left NASA scientists with more questions than answers.“甲烷气体浓度的上升和下降给NASA的科学家们留下了更多的问题而不是答案。”由此可知，人类的探索告诉了我们“火星上的甲烷气体水平是不稳定的。”故选D。

3.推理判断题。根据第五段中This time, NASA said the measured methane gas level was clearly larger than any others observed in the past. "It's exciting because microbial (微生物的) life is an important source of methane on Earth," NASA said in a statement announcing the discovery. 这一次，美国宇航局表示，测量到的甲烷气体水平明显比以往任何一次观测到的都要高。NASA在宣布这一发现的声明中说:“这很令人兴奋，因为微生物是地球上甲烷的重要来源。”由此可知，在NASA看来，这一发现意味着“火星上可能存在生命。”故选A。

4.推理判断题。根据最后一段中We're more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Marian atmosphere.“我们比以往任何时候都更有动力去持续测量，并把我们的大脑放在一起，以弄清楚甲烷在Marian大气中的行为。”由此可知，美国宇航局的科学家们对他们未来的探索是“自信的”。故选B。