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  3. Is there life anywhere in the universe other than on Earth? To answer that

Is there life anywhere in the universe other than on Earth? To answer that

游客2024-08-19  42
问题       Is there life anywhere in the universe other than on Earth? To answer that question, scientists look at outer space through telescopes.They send up rockets and satellites and study the information that comes back.Scientists also study life forms on Earth.They think about the features on Earth that support life.Every answer helps them to know what to look for in outer space.

      Researchers have learned that two things are required to keep life going on Earth.They are energy and flowing water.All life forms need water to survive.It takes energy to keep water in its liquid state, however.Earth’s energy comes from the sun.Our source for water is rain and snow, which are collected by oceans, lakes, rivers and streams.
      What places in our solar system are likely to have energy to keep water in a liquid state? The answer to that question is unknown, but scientists have some ideas.They are looking very closely at the planet Mars.Although the atmosphere of Mars is very different from Earth’s atmosphere, it does have water.Martian air holds only about 1/1000 as much water as Earth’s air.Even that small amount can produce clouds, fog, and frost—all filled with water.The greatest problem with keeping water in a liquid state on Mars is the planet’s extreme cold.The average temperature on Mars is -81 degrees Fahrenheit.The warmest, it gets is 68 degrees Fahrenheit, and the coldest recorded temperature is -220 degrees Fahrenheit!
      Life may also be possible on Europa, one of the moons of the planet Jupiter (木星).Scientists believe that Europa may have liquid water and volcanoes.The heat from volcanoes may keep oceans from freezing.Scientists are planning missions to Jupiter and Europa to bring back samples of surface ice.They suspect that if there is life on Europa, it may exist in an ice-covered ocean.They believe that deep below the ice, hot springs in the ocean floor heat the water.
      Scientists also look at life on Earth to ponder questions about life in outer space.Life forms have adapted to some remarkably harsh conditions.Creatures too tiny to be seen with the human eye live in ice-covered Antarctic lakes and in steaming hot springs.Infrequently, small creatures can even be found in the dry centres of rocks.The existence of these life forms suggests that some very harsh places can support life.As scientists unlock the secrets of how living things survive on this planet, they come closer to answering questions about life forms elsewhere in our solar system and beyond.
      Scientists use【A1】_________and space missions to study outer space to determine if there is life beyond Earth.After looking at life forms on Earth, scientists believe that living things need【A2】_________and energy.The planet 【A3】_________has water, while Jupiter’s moon Europa may have liquid water and【A4】_________.It’s amazing that life exists on Earth in places as frozen as Antarctica.Scientists continue to look closely at【A5】_________that support life on Earth for clues to where life may exist in other parts of the universe. [br] 【A2】
选项
答案 liquid/ flowing water
解析 文章第二段第二句提到，维持地球上的生命需要能量和流动的水。因此，填入liquid或flowing water。
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