托福阅读真题+题目+答案：The Early History of Jupiter

托福阅读真题+题目+答案：The Early History of Jupiter

The Sun and all planets in the solar system formed from the same cloud of interstellar material known as the solar nebula. However, the size and composition of the four outer Jovian planets (Jupiter, Saturn, Uranus, and Neptune) radically differ from those of the four terrestrial planets, which are closest to the Sun (Mercury, Venus, Earth, and Mars). Whereas the inner planets are composed mainly of heavier elements, the Jovian planets are much larger and contain a much higher proportion of the light gases hydrogen and helium. Jupiter, with its mass of around 300 times that of Earth, is the largest planet in the solar system and is the Jovian planet closest to the Sun.

1.The word “radically'' in the passage is closest in meaning to

O slightly

O certainly

O eventually

O fundamentally

2.According to paragraph 1, all of the following statements about the Jovian planets are true EXCEPT:

O They all formed from material present in the solar nebula.

O They are all further away from the Sun than the terrestrial planets are.

O They all contain a lower proportion of heavy elements than terrestrial planets do.

O They all have a mass that is at least 300 times greater than Earth's mass.

It is generally believed that Jupiter's formation began with the accretion (the coming together of material under the influence of gravitation) of a solid core. This core grew by collision and sticking of dust, ice, rocks, and larger bodies- -a process similar to the accretion of Earth. Jupiter, however, formed outside, or beyond, the“snow line," a special place in the solar system where water vapor condensed (solidified) to form ice grains, and the presence of“snow" in this region would enhance the density of solid matter and accelerate the accretion process. The mystery is why the proto-Jupiter (early Jupiter) grew so rapidly. Apparently, Jupiter grew to a mass of 15 Earths before Mars grew to 10 percent of an Earth mass. Planetary scientist David Stevenson has suggested that outward migration of water vapor and condensation at the“snow line" may have provided larger concentrations of solid matter at this location, thus speeding up the formation of the early Jupiter.

3.Paragraph 2 suggests which of the following about Earth's formation?

O It occurred outside the “snow line."

O It occurred after the formation of Jupiter.

O It slowed when Earth reached 10 percent of the size of Mars.

O It included a period when solid materials were brought together by gravity.

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