Artist’s reconstruction of Gangtoucunia aspera as it would have appeared in life on the Cambrian seafloor, circa 514 million years ago. The individual in the foreground has part of the skeleton removed to show the soft polyp inside the skeleton. Credit: Reconstruction by Xiaodong...
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. ...
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...
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...
Importance of the morphology of the carbonaceous remains; Information on the discovery of life on earth on basis of carbonaceous residues.HollandHeinrich D.ScienceHolland HD. Evidence for life on Earth more than 3850 million years ago. Science 1997;275:38-9....
Life began on earth million of years ago. Though there are (16) beings (17) opportunity given by existence, by looking beyond their desires. Life can be used,
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...
解析 【答案】have been【详解】 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 时间状语In the last 500 million years可知, 句子用现在完成时。 此处考查there be句 型, 主语five times为复数形式, 助动词用 have。 故填have been。
The usual way is on the back of a mule. 现在,我们已到了离大峡谷缘下面 大约500 英里的地方 Here, we're about 500 feet below the lip of the canyon. 这里的岩石已经有两千万年了 Already the rocks are about 200 million years old. 这里还没有哺乳动物 但是已经有了一些四脚的陆地动物 ...
【题目】Scientists think there has been life on Earth for ___ years. A.millions ofB.hundreds ofC.five million ofD.million of 试题答案 在线课程 【答案】A 【解析】 句意:科学家认为地球上有生命已经有成百万上千万年了。A.成百万上千万B.成百上千C.错误选项,应改为five million(五百万)D.错误选...