托福阅读真题+题目+答案：Origins of Earth's Salty Oceans

托福阅读真题+题目+答案：Origins of Earth's Salty Oceans

Scientists have long been interested in discovering the origin of Earth's water and establishing why Earth's oceans are so salty There has been speculation that earliest Earth was so hot that no liquid water existed, and all light elements (such as hydrogen and oxygen) were rapidly stripped away from Earth by the solar wind (a stream of charged particles emitted by the Sun). If this were true, then the elements needed to form water on Earth would not have been freely available. As a consequence, it was proposed that collisions with icy comets or similar gas-and water-rich materials brought water to Earth after the planet had sufficiently cooled to retain it. This concept was supported by comparisons of the gas compositions of meteorites with those of rocks from beneath Earth's surface, notably using krypton and xenon, nonmetallic gases that do. not react with other materials. There certainly is enough ice in space to have supplied our water (and atmosphere)in this manner.

1.The word "notably" in the passage is closest in meaning to

A simply

B expertly

C in particular

D by necessity

2.According to paragraph 1 the proposal that Earth water was likely related to comets depends on which.TWO of the following beliefs? To receive credit, you must select TWO answer choices.

A Earth was too hot for water to exist.

B Earth had cooled too rapidly for the presence of the elements needed for water.

C The elements that made up meteorites and rocks could not have produced water.

D Elements required for water to form were stripped away by solar wind.

In July 2015, the space probe Philae. which landed on comet Churi, discovered not only ice and dust, but also 16 types of organic compounds, present not in a loose distribution but in discrete clumps. Suddenly, the idea gained lots of traction that comets brought not only water, but also the ingredients for life, even in ready-made clumps. Intriguingly, in October 2015 it was reported. that-as this comet slowly thaws-molecular oxygen(02) escapes in a constant and high proportion(1% to 10%) relative to water which suggests that the comet also contains a surprising amount of primordial (ancient) oxygen, which was incorporated during the comet's formation.

3.The phrase"gained lots of traction" in the passage is closest in meaning to

A was quickly resisted

B became much more popular

C was frequently suggested

D created much argument

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