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
21
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.
【C6】
选项
A、Provided
B、Hence
C、Since
D、Unless
答案
C
解析
结合本段首句中提到的“科学家估计约有5%的行星具有跟地球相似的质量”,可以认为此句逗号前的分句“单单在银河系中就存在大约2,000亿颗恒星”是逗号后句子“科学家们估计大约会有100亿颗地球体积大小的行星存在”的依据。C项Since可引导原因状语从句,指“由于,因为”,用法、语义均符合要求。
转载请注明原文地址:https://kaotiyun.com/show/icbZ777K
0
考研英语一
相关试题推荐
Ittakesawholegalaxyofthingstomakeyouhappy.Happinessisastateyoufeelwhenyouhavenoproblems,worries,doubtsor
Divorceisoneofthosecreations,likefastfoodandliterock,thathasmorepeoplewillingtoindulgeZinitthanpeoplewill
Divorceisoneofthosecreations,likefastfoodandliterock,thathasmorepeoplewillingtoindulgeZinitthanpeoplewill
"Always"."Never".TheseareprobablythetwomostpowerfulwordsintheEnglishlanguage.Evenmorepowerfulthanyesandno,s
Ananalysisof20,928postmenopausalwomenshowedthatthetallerawomanis,thegreaterherriskforanumberofcancers,incl
Ananalysisof20,928postmenopausalwomenshowedthatthetallerawomanis,thegreaterherriskforanumberofcancers,incl
Ifplanningofferssomanytangiblebenefits,whydomanyprofessionalsresistit?Somearemorecomfortablewithacting,rather
Anumberofethicalquestionsclusteraroundbothendsofthehumanlifespan.Whetherabortionismorallyjustifiablehaspopul
TheU.S.spaceagency,NASA,isplanningtolaunchasatellitethatscientistshopewillanswerfundamentalquestionsaboutthe
Sevenyearsago,agroupoffemalescientistsattheMassachusettsInstituteofTechnologyproducedapieceofresearchwhichsh
随机试题
港口与航道工程中,高桩码头混凝土预制构件在预制场存放时应符合下列规定:()。
测定肾小球滤过率的物质应具有
近代意义宪法产生以来,文化制度便是宪法的内容。关于两者的关系,下列哪一选项是不正确的?(2013年卷一23题,单选)
以下运用人本原理的原则的是()。
我国现行个人所得税采取的征收制度是()。
甲某对其外甥说:“如果你在数学竞赛中获得第一名,就赠给你电脑一台。”其外甥欣然同意,当其外甥在竞赛中获得第一名时,甲某表示,该电脑自己正在使用,不愿再将电脑赠给他。对此,下列表述正确的是()。
在人们创造历史的活动中,谋事在人,成事在天。()
法国革命势力最后战胜封建势力是在()。
中国佛教四大名山分别是山西五台山、________、四川峨眉山、安徽九华山。
Access报表对象的数据源可以是
最新回复
(
0
)