小伙伴们，GRE考试大家复习的怎么样了呢？下面是帮考网分享的一些GRE考试阅读部分的复习资料，一起来看看吧！

When Earth formed 4.6 billion years ago, the Sun burned only 70 percent as brightly as it does today. Yet Geologic record contains no evidence for widespread glaciation until 2.3 billion years ago. Sagan and Mullen suggested in the 1970s that ammonia, a greenhouse gas, warmed early Earth’s atmosphere, but subsequent research showed that the Sun’s ultraviolet rays rapidly destroy ammonia in an oxygen-free environment, such as that of early Earth. Many scientists now attribute much of the warming of early Earth to oxygen-intolerant microbes—methanogens—that produce the greenhouse gas methane. The methanogen hypothesis could help to explain the first global ice age: 2.3 billion years ago, Earth’s atmosphere began to fill with oxygen produced by other microbes—cyanobacteria—causing methanogens to decline rapidly.

1. Which of the following best describes the function of the highlighted sentence?

A. It refutes the possibility of a connection between two events previously thought to be related.

B. It describes how a hypothesis might account for the timing of a phenomenon described earlier in the passage

C. It presents evidence that casts doubt on a statement made in the first sentence of the passage

D. It clarifies a distinction between two related hypotheses

E. It introduces findings that challenge a dominant explanation for a particular phenomenon

2. Which of the following can be inferred from the passage about methanogens?

A. Methanogens must have appeared on Earth later than 2.3 billion years ago.

B. Methanogens must have been much more prevalent in some regions of the early Earth than in others.

C. Methanogens produce a greenhouse gas that is more susceptible to destruction by the Sun’s ultraviolent rays than is ammonia.

D. Methanogens could not have thrived in early Earth’s atmosphere without the presence of ammonia.

E. Methanogens would have had a less significant effect on early Earth’s atmosphere if they had evolved after the appearance of cyanobacteria.

1

When Earth formed 4.6 billion years ago, the Sun burned only 70 percent as brightly as it does today.

46 亿年前地球刚形成时，太阳燃烧发出的亮度值相当于今天的七成。

2

Yet Geologic record contains no evidence for widespread glaciation until 2.3 billion years ago.

然而地质记录中直到 23 亿年前才首次出现广泛的结冰期的证据。

3

Sagan and Mullen suggested in the 1970s that ammonia, a greenhouse gas, warmed early Earth’s atmosphere, but subsequent research showed that the Sun’s ultraviolet rays rapidly destroy ammonia in an oxygen-free environment, such as that of early Earth.

S 和 M 于 1970 年代提出氨，一种温室气体，导致地球大气暖化，但随后的研究表明，太阳紫外线在无氧环境中快速分解了氨，这正如形成初期的地球的大气环境。

4

Many scientists now attribute much of the warming of early Earth to oxygen-intolerant microbes — methanogens — that produce the greenhouse gas methane.

现在，许多科学家把早期地球暖化，主要归因于厌氧微生物 —— 甲烷菌 ——它产生温室气体甲烷。

5

The methanogen hypothesis could help to explain the first global ice age: 2.3 billion years ago, Earth’s atmosphere began to fill with oxygen produced by other microbes — cyanobacteria — causing methanogens to decline rapidly.

甲烷菌假设，可以帮助解释第一次全球结冰期：23 亿年前，地球大气开始充满其他微生物 —— 藻青菌生产的氧气 —— 致使甲烷菌迅速减少。

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