2019年7月7日托福阅读真题+题目+答案：Water and Life on Mars

2019年7月7日托福阅读真题+题目+答案：Water and Life on Mars

The question of life on Mars depends heavily on the characteristics of its air and water. Mars has a relatively thin and dry atmosphere, with high percentage of carbon dioxide compared to Earth's atmosphere. Mars tilts about25°,which leads to seasons like those on Earth. Carbon dioxide freezes into the polar caps during the winter and evaporates into the air in the summer This causes a fluctuation in the density of the atmosphere of up to 25 percent over the year With so little atmosphere, the planet experiences a wide range of temperatures, heating up in the day and rapidly cooling at night. Temperatures on Mars have been measured between-225F and 95°

1.According to paragraph 1, all of the following are true about the planet Mars EXCEPT:

O It has as an atmosphere with a stable density year-round.

O It has a greater amount of carbon dioxide than Earth has.

O It has number of different seasons.

O It experiences significant temperature variations.

Scientists remain fascinated by the possibility of liquid water on Mars. Life as we know it requires water so it should be good marker for habitability. ⬛ Current conditions on Mars suggest that liquid water could not occur on the surface. ⬛ The low pressure and low temperature mean that ice would sublime-go straight from solid to gas-rather than melt. ⬛ Water may be hiding in subsurface reservoirs, however, and stream forth for limited periods. ⬛ In 2002 the Mars Odyssey orbiter detected large quantities of water ice near the surface of the southern hemisphere Channels on the surface suggest the presence of moving water in large quantities. In 2006 Mars Global Surveyor provided pictures of gullies (channels) on the surface that could only have been produced by liquid water flowing within the past seven years. Theories exist for how climate and erosion may reveal underground ice and cause sudden floods, but specific details are still a mystery. The water probably represents flash floods that quickly evaporate and may not provide an adequate medium for the development of life. If life arose in the distant past, though, the selfish floods may have been enough to maintain organisms adapted to such environments.

2.According to paragraph 2,evidence from the 2002 Mars Odyssey orbiter supports which of the following possibilities about water on Mars?

O The near surface of the southern hemisphere contains more water in liquid for m than in ice form.

O The amount of moving water on the surface of Mars is probably greater than that hiding in subsurface reservoirs.

C The occurrence of flash floods on Mars is enough to maintain certain species of organisms.

O Water may be present under the surface of Mars and flow for short periods of time.

3.In paragraph 2, the findings of the 2006 Mars Global Surveyor suggest which of the following is likely to be true about Mars?

O The climate of Mars has changed greatly over time.

O Life could not have existed on Mars during the planet's early history.

O The surface of Mars experiences erosion and sudden flooding.

O Water on the surface of Mars is very slow to evaporate.

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