Two-billion-year-old shungite, a type of sedimentary rock exposed in north-western Russia, records evidence for balmy, oxygen-rich conditions on the early Earth. Credit: K. Paiste. Shungite, a unique carbon-rich sedimentary rock from Russia deposited 2 billion years ago, holds clues about oxyg...
Scientists believe that 4.5 billion years ago, Mars and Earth began their existence undersimilar conditions. During the first billion years,liquid water—in contrast to ice-was abundant onthe surface of Mars. This is an indication that Mars was much warmer during that time. Mars alsohad a thic...
14-4The Formation of the Earth Billions of years ago, the sun formed. There was a huge disk of rocks and gases in the solar system. Eventually,these rocks and gases began to form planets. This was about 4.5 billion years ago. Earth was the third planet from the sun. At first, the ...
(1)D.形容词辨析.A更老的,B更大的,C更小的,D更年轻的,根据上句Scientist believe the earth is 4.6 billion (十亿)years old.科学家认为地球有46亿年的历史。这里应该是我们今天看到的沙漠和森林比这要年轻得多,故答案是D.(2)B.副词辨析.A几乎不,B只,C相当地,D永远,根据The Baltic Sea, the younges...
解析:题干大意:科学家估计,地壳在30亿年前就开始变化。文章第三段第二句提到:They’ve found new evidence suggesting that Earth’s crust started shifting atleast 3.8 billion years ago.他们发现新证据——地壳至少在38亿年前就开始变化。题干所述把文章信息的年份缩短了,故答案选B。反馈 收藏 ...
But the best thing about it is that, unlike coal and gas, it doesn't run out. The Solar Impulse plane could pretty much keep flying forever. Of course, the sun's light will run out one day, but not for another 5 billion years. That's a pretty long flight.1. The plane Solar ...
Well, actually, the sun will run out too, one day, but not for another 5 billion years. That’s a pretty long flight 1. What does “chariot” really refer to in the last sentence of Paragraph 1? A. The Earth B. The Greek god C. Solar Impulse D. Birds 2. Which of the ...
Of course, the sun’s light will finally run out too one day, but not for another 5 billion years. That’s a pretty long flight. 1. The Solar Impulse ___. A. has to take a break at night B. is powered by chemicals C. has already flown across the US D. is a special kind o...
Scientists have long believed that Earth in its early years hadan atmosphere and oceans that...Chen, Cathaleen
Since it formed over 4.5 billion years ago, Earth has been hit more people to die of 66.n(starve).61.(occasional) by asteroids (小行星) and comets 62.The new awareness of asteroid impacts has increased the appreciation of orbits bring them into the inner solar system. These objects, ...