425 million years ago Thecoelacanths, a group of famous “living fossils” – species that have apparently not changed for millions of years – may have split from the rest of the lobe-finned fish at this time.Coelacanthsbegin appearing in the fossil record by409 million years ago. 417 mil...
In the last 500 million years, there have been five times 1 life on Earth has almost ended. Many 2 (scientist) say we are now entering the Earth’s sixth mass extinction. There is 3 long list of reasons why so many species 4 (die) out. This time, human activity will be 5 (blame...
根据"there has been life on the earth"可知,这里用的是现在完成时态,结合题目要用介词来填空,for+一段时间,since+时间点或者从句;hundreds of millions of years指的是一段时间,因此应用介词for。故填:for。【思路点拨】科学家们认为地球上的生命已经存在了数亿年。【解题思路】理解题干,结合语境,填写正确...
我们谈论的同时大约在4亿年前 At the time of which we are talking, about 400 million years ago, 地球的面貌和现金迥然相异 the face of the earth was not at all like what it is today. 大洲海洋盆地海岸线之间的关系都不尽相同 The relationships of the continents, the ocean basins, the ...
Therehasbeenlifeonearthfor___years.( ) A. million B. amillionof C. millionsof 相关知识点: 试题来源: 解析 C 答案:C 考查数词的用法.millions of+名词复数;one/two million 固定用法,所以选择C.地球上的生命已经有几百万年了.考查数词的用法,掌握固定用法是解题的关键.反馈 ...
考查therebe句型和时态。句意:在过去的5亿年里,地球上有五次生命几乎灭绝。根据句中时间状语In the last 500 million years可知,用现在完成时。表示“有”可用there be句型。“5次”翻译为 five times,为复数形式,谓语动词用have。故填have been five times。反馈...
In the last 500 million years, there have been five times when life on Earth has almost ended. A 2015 study by scientists 1 were based on Brown University and Duke University in the US, look at 2 quickly species die out due to natural causes. They found that human activity is causing ...
In the last 500 million years, there have been five timeslife on Earth has almost ended. (用适当的词填空) 相关知识点: 试题来源: 解析 when 【详解】 考查定语从句引导词。句意:在过去的5亿年里,地球上的生命有5次濒临灭绝。分析句子可知,空格处引导定语从句,先行词为times,关系词在从句作时间状语,...
Ⅳ.课文语法填空In the last 500 million years, there have been five times when life on Earth has almost ended. The reasons for extinctions are _1_ (vary). According to scientists, they include volcanic 2(erupt), asteroids hitting the Earth from space, changes in se a levels, the decrease...
Passage One Animal life first appeared on the earth about 400 million years ago. Through the passing millennia, thousands of animal species have come and gone. Until recently, this process was gradual, the result of changes in climate, in habitat, or in the genes of the animals themselves. ...