托福阅读真题+题目+答案：Life on Europa

托福阅读真题+题目+答案：Life on Europa

For decades, it was believed that life in the solar system can exist only in the ideal zone around the Sun, where planets are not too hot or too cold to sustain life. Liquid water will boil on a planet like Mercury, which is too close to the Sun, and will freeze on a planet like Jupiter, which is too far, whereas Earth is blessed with liquid water because it orbits at just the right distance. Since liquid water is probably the fluid in which DNA and proteins were first formed, it was long believed that life in the solar system can exist only on Earth, or perhaps Mars. But astronomers were wrong.▋ After the Voyager spacecraft sailed past Jupiter in 1979. it became apparent that there was another place for life to flourish: under the ice cover of Europa one of the moons of Jupiter discovered by Galileo in 1610. ▋Although its surface is permanently covered with ice, beneath that ice there is a liquid ocean. Moreover, there is much more water in this ocean than might be expected on such a relatively small body. ▋Because the ocean is much deeper on Europa than on Earth, the total volume of Europa's ocean is estimated to be twice the volume of Earth's oceans.▋

1.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

A.Earth orbits the Sun at the right distance to have liquid water, whereas planets like Mercury and Jupiter do not.

B.As a result of its orbit around the Sun, Earth is significantly cold than Mercury and significantly hotter than Jupiter.

C.Mercury is much closer to the Sun than it is to Earth, and Jupiter is much farther away from the Sun than Earth is.

D.Although Mercury, Earth, and Jupiter orbit the Sun at different distances, they are all blessed with water-boiling, liquid, or frozen.

2.According to paragraph 1, astronomers were incorrect in believing which of the following about liquid water?

A.Life requires liquid water.

B.Liquid water may exist on Mars.

C.DNA and proteins first formed in liquid water.

D.Liquid water exists only at a certain distance from the Sun.

It was a bit of a shock to realize that there is an abundant energy source in the solar system other than the Sun. Underneath the ice, the surface of Europa is continually heated by tidal forces (the gravitational forces exerted on one body by another). As Europa moves in its orbit around Jupiter, that massive planet's gravity squeezes Europa in different directions, creating friction deep within its core. This friction creates heat, which in turn melts the ice and creates a stable ocean of liquid water. This discovery means that perhaps the moons of distant gas giants are more interesting than the planets themselves. Life, which was once thought to be quite rare might actually flourish in the blackness of space on the moons of distant gas giants. Suddenly, the number of places where life might flourish has increased many times.

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