首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Now that we are fairly sure that there are many Earth-like planets in the Galaxy, the time is ripe (or almost so) to wonder whet
Now that we are fairly sure that there are many Earth-like planets in the Galaxy, the time is ripe (or almost so) to wonder whet
admin
2017-08-11
68
问题
Now that we are fairly sure that there are many Earth-like planets in the Galaxy, the time is ripe (or almost so) to wonder whether these new worlds do indeed have a high probability of hosting new forms of life.
Currently, the best【C1】______on the existence of other planets comes from NASA’s【C2】______Kepler satellite, which has been mapping an area of the sky【C3】______some 150,000 stars.
Scientists estimate that around 5 percent of planets in our galaxy have masses similar【C4】______Earth’s and, possibly, are within the habitable zone of their stars, meaning that【C5】______they hold water it has a high chance of being liquid.【C6】______there are about 200 billion stars in our galaxy alone, scientists estimate that there should be about 10 billion Earth-size planets. Not bad, especially if we【C7】______that to be Earth-size and within a habitable zone is all it takes for life to take hold in an【C8】______world. In practice, however, the situation is much more【C9】______, since it depends on what life is and how it appears in a planet,【C10】______on the planet’s detailed geological history.
Here on Earth life appeared some 3.5 billion years ago.【C11】______that it may have been here as far【C12】______as 3.8 billion years ago remain tentative. For about the first three billion years, life on earth was【C13】______in the form of single-cell creatures. Only when Earth’s atmosphere was full of oxygen did more sophisticated organisms appear.
【C14】______its unusual atmosphere, Earth’s heavy, single moon, its magnetic field also did something else that allowed complex life to【C15】______on its surface.【C16】______these, Complex life would find it very hard to【C17】______and survive.
The results from Kepler’s mission are encouraging and exciting. We have the【C18】______of confirming the existence of countless other worlds out there. Based on these findings, we should indeed【C19】______that other worlds would host some kind of simple life. However, as some scientists argued, Earth and its ability to host complex life will probably remain a【C20】______phenomenon in this and other galaxies.
【C12】
选项
A、back
B、away
C、forward
D、down
答案
A
解析
如果生命在38亿年前(3.8 billion years ago)就出现的话,也意味着它的出现时间应追溯回更遥远的古代。A项back代入as far…as的表达后,组成了一个惯用表达,意为“早在(……时间),最早至……”。
转载请注明原文地址:https://kaotiyun.com/show/ScbZ777K
0
考研英语一
相关试题推荐
Ittakesawholegalaxyofthingstomakeyouhappy.Happinessisastateyoufeelwhenyouhavenoproblems,worries,doubtsor
Divorceisoneofthosecreations,likefastfoodandliterock,thathasmorepeoplewillingtoindulgeZinitthanpeoplewill
Thebestsolutionistostoppretendingthatpeople’spersonalinformation,suchasSocialSecurityaccountnumbersandbirthda
Ananalysisof20,928postmenopausalwomenshowedthatthetallerawomanis,thegreaterherriskforanumberofcancers,incl
Manyscientistsconsiderphysicsastheprototypeofascience,andindeed,physicsexhibitsanumberoffeatureswhichcanber
Manyscientistsconsiderphysicsastheprototypeofascience,andindeed,physicsexhibitsanumberoffeatureswhichcanber
【F1】Waterpollutioninvolvesthereleaseintolakes,streams,rivers,andoceansofsubstancesthatbecomedissolvedorsuspende
TheU.S.spaceagency,NASA,isplanningtolaunchasatellitethatscientistshopewillanswerfundamentalquestionsaboutthe
It’seasytoscarepeopleaboutwhat’sintheirfood,butthedangerisalmostneverreal.Andthe【C1】______itselfkills.Ta
随机试题
A.手三里B.睛明C.瞳子髂D.曲泽既可直刺、深刺,又可针刺放血的腧穴是
成人慢性牙周炎的基础治疗是
影像增强器的增益中包括
A.医德认识B.医德情感C.医德意志D.医德信念E.医德行为
按现行国家标准规定,设计照度值与照度标准值比较,允许的偏差是哪一项?()
城市道路衔接的原则不包括:
《会计法》所称的内部会计监督的对象是指()。
按《营业税暂行条例实施细则》的规定,企业下列行为中属于兼营应税劳务与货物或非应税劳务的是( )。
()之于精当相当于固若金汤之于()
A、 B、 C、 A在回答由When(时候)开始的提问时,要接由表示时间的词构成的句子。正确答案是(A)“在周末结束之前”。而(B)完全不符合逻辑,至于(C)是因为重复使用building而设的陷阱。
最新回复
(
0
)