首页
登录
职称英语
When Earth formed 4.6 billion years ago, the Sun burned only 70 percent as b
When Earth formed 4.6 billion years ago, the Sun burned only 70 percent as b
游客
2025-02-19
28
管理
问题
When Earth formed 4.6 billion years ago, the Sun burned only 70 percent as brightly as it does today. Yet geologic record contains no evidence for widespread glaciation until 2.3 billion years ago. Sagan and Mullen suggested in the 1970s that ammonia, a greenhouse gas, warmed early Earth’s atmosphere, but subsequent research showed that the Sun’s ultraviolet rays rapidly destroy ammonia in an oxygen-free environment, such as that of early Earth. Many scientists now attribute much of the warming of early Earth to oxygen-intolerant microbes—methanogens—that produce the greenhouse gas methane.
The methanogen hypothesis could help to explain the first global ice age: 2.3 billion years ago, Earth’s atmosphere began to fill with oxygen produced by other microbes—cyanobacteria— causing methanogens to decline rapidly.
[br] Which of the following best describes the function of the highlighted sentence?
选项
A、It refutes the possibility of a connection between two events previously thought to be related.
B、It describes how a hypothesis might account for the timing of a phenomenon described earlier in the passage
C、It presents evidence that casts doubt on a statement made in the first sentence of the passage
D、It clarifies a distinction between two related hypotheses
E、It introduces findings that challenge a dominant explanation for a particular phenomenon
答案
B
解析
本题属于功能题,根据句间关系可知这句话用于支持前一句,即甲烷菌假说可以解释地球的冰川现象发生时间,因此选项B正确。a hypothesis对应The methanogen hypothesis,a phenomenon指第二句的widespread glaciation,timing指的是23亿年之前。A项本文唯一可以用作反驳功能的,只有第三句的but部分。C项第一句呈现的是事实,而非观点,无法被质疑。D项这句话仅仅在解释甲烷菌假说本身,没有涉及之前萨根和马伦的假说。E项这句话用来支持而不是质疑甲烷菌假说,而且a dominant explanation在文中没有对应。
转载请注明原文地址:https://tihaiku.com/zcyy/3964183.html
相关试题推荐
Ourterrestrialfoodsupplycomesfromecosystemstransformedtoproduceaf
Describeateamyouhavebeenpartof.Youshouldsay:whenthisteamwasformed
Thechartshowshouseholdsavingsasapercentageofincomeforpeopleliving
Thetablebelowgivesinformationaboutthepercentageoflandcoveredbyfo
Thebarchartshowsthepercentageofpeoplewhosmokedineightcountriesin
Thechartbelowshowsthetotalnumberofminutes(inbillions)oftelephone
Thelinegraphshowsthepercentageofpeoplewhohavecriminalrecordsatd
Thechartbelowshowsthetotalnumberofminutes(inbillions)oftelephone
Thetableshowsthepercentagesgovernmentsspendoneducationandtraining
Thechartsbelowshowthepercentageofwaterusedfordifferentpurposesinsix
随机试题
Archaeologyasaprofessionfacestwomajorproblems.First,itisthepoore
Secondlanguageteachingshouldfocusonencouragingacquisition,andonpro
Logistically,itworkedoutbestformetoflyeastfromBostonLogantoLon
氟哌利多作用特点是A.镇静作用稍逊于氯丙嗪 B.有强大的镇吐作用 C.抑制心
A.保钠、保水 B.嗜酸性粒细胞减少 C.中性粒细胞减少 D.血小板减少
教师罚学生抄写课后生字5遍,学生的这种抄写行为属于操作技能练习。
以下几个指标,专门针对商业银行等金融机构的是()。A.5Cs系统 B.5
某国家重点建设工程在申办施工许证的过程中,下列选项中不符合法规规定颁发施工许可证
关于期货合约和远期合约的比较,下列叙述不正确的是()。A.期货合约在交易所交易
欲检测生产场所粉尘的浓度、分散度和游离二氧化硅含量三个项目。 物镜测微尺是用于
最新回复
(
0
)