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
专升本
For many years, scientists couldn’t figure out how atoms and molecules(分子)on the Earth combined to make living things. Plants, f
For many years, scientists couldn’t figure out how atoms and molecules(分子)on the Earth combined to make living things. Plants, f
admin
2018-08-16
25
问题
For many years, scientists couldn’t figure out how atoms and molecules(分子)on the Earth combined to make living things. Plants, fishes, dinosaurs(恐龙), and people are made of atoms and molecules, but they are put together in a more complicated way than the molecules in the primitive ocean. What’s more, living things, that have energy and can reproduce on the Earth four billion years ago were lifeless.
After years of study, scientists figured out that living things, including human bodies, are basically made of amino acids and nucleotide(氨基酸与核苷酸)bases. These are molecules with millions of hydrogen(氢), carbon(碳), nitrogen(氮), and oxygen atom. How could such complicated molecules have been formed in the primitive soup? Scientists were stumped(难住).
Then, in 1953, two scientists named Harold Urey and Stanley L. Miller did a very simple experiment to find out what had happened on the primitive Earth. They set up some tubes and bottles in a closed loop(线圈), and put in some of the same gases that were present in the atmosphere four billion years ago: water vapor, carbon dioxide(二氧化碳), methane(甲烷), and hydrogen.
Then they shot an electric spark through the gases to simulate(模拟)bolts(闪电)of lightning on the ancient Earth, circulated the gases through some water, sent them back for more sparks, and so on. After seven days, the water that the gases had been bubbling(起跑)through had turned brown. Some new chemicals were dissolved in it . When Miller and Urey analyzed the liquid, they found that it contained amino acids—the very kind of molecules found in all living things.
Harold Urey and Stanley L. Miller did their experiment in order to______.
选项
A、find out what had happened on the Earth 4 billion years ago
B、simulate bolts of lightning on the ancient Earth
C、dissolve some new chemicals
D、analyze a liquid
答案
A
解析
文章第三段…Harold Urey and Stanley L.Miller did a very simple experiment to find out what had happened on the primitive Earth及第二句中的4 billion years ago,由此可知这里的primitive Earth是指4 billion years ago,所以A为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/kSPC777K
本试题收录于:
英语题库普高专升本分类
0
英语
普高专升本
相关试题推荐
A、Equippingstudentswithknowledge.B、Qualifyingstudentsforcertainjobs.C、Developingstudents’habitsofmind.D、Helpingst
Howdoyouknowifyourhomeisaneasyaimforthefts?Aroundtheholidays,manyfamiliesdon’tconsidertakingpropermeasures
Nobodywantstobesick.Unfortunatelyourbodiescandevelopproblems.Whenwearen’thealthy,ourbodiestellus.Sometimesa
Advertisingfollowsuseverywhere.Wheneverweturnonthetelevision,listentotheradiooropenanewspaperoramagazine,we
Themotorvehiclehaskilledanddisabledmorepeopleinitsbriefhistorythananybomborweaponeverinvented.Muchofthebl
Morethanfortythousandreaderstolduswhattheylookedforinclosefriendships,whattheyexpected【C1】______friends,whatth
Thelocalgovernmentacceptedtheproposalputforwardattheconferencethepublictransportationbeimproved.
Itiseasierto______aconversationwithothersbytalkingabouttheweather.
Thenthedoctorsexaminedthemandfound______.
Itisa______tohearhisspeech.
随机试题
下列各项中,属于领导方法的特征的是
小儿器质性腹痛的常见临床表现有
体重指数(BMI)低于()时称为消瘦。
某法院在审理一行政案件中认为某地方性法规与国家法律相抵触。根据我国宪法和法律的规定,下列表述何者为正确?
国际快递业务的形式分()。
输入动植物,需隔离检疫的,在口岸出入境检验检疫机关( )检疫。
“十个手指有长短”这句话表明,在学生发展过程中存在()。
根据下面材料回下列小题。总体看来,2004年世界各国的石油探明储量基本变化不大。但是由于BP公司修正了苏联、哈萨克斯坦、伊朗、利比亚和苏丹等国的数据,特别是哈萨克斯坦从12亿吨修正到54亿吨,从而使各国在全球石油储量分布中所占的比例发生了一些变化
2017年9月29日,世界首条量子保密通信干线——“()”正式开通。
设A=,B=(kE+A)2,(k为实数)求对角矩阵D,使B与D相似;并问志取何值时B为正定矩阵?
最新回复
(
0
)