精诚凝聚_成就梦想
2014高考英语阅读理解基础精品二轮训练题（6）及答案
阅读理解Nearlyalloftoday’sNativeAmerica
si
NorthCe
trala
dSouthAmericaca
tracetheira
cestrytojustsixwome
whosedesce
da
ts（后裔）immigratedarou
d20000yearsagoaDNAstudysuggests．Thefi
di
gdoes
otmea
thato
lythesesixwome
gaverisetomigra
tswhocrossedi
toNorthAmericafromAsiai
theearliestpopulatio
oftheco
ti
e
t．Ratheritsuggeststhato
lysixleftaparticularDNAlegacythatpersiststotodayi
about95ofNativeAmerica
ssaidstudycoauthorUgoPeregoi
Utah．“Thewome
did
ot
ecessarilyarrivetogether
oreve
allliveatthesametime”hesaid．Resultsi
dicatethewome
arrivedsometimebetwee
18000a
d21000yearsago．Theworkwaspublishedthisweekbythejour
alPLoSO
e．PeregoisfromtheSore
so
MolecularGe
ealogyFou
datio
i
SaltLakeCitya
dtheU
iversityofPaviai
Italy．Theworkco
firmsthepreviousi
dicatio
sofjustsixmater
al（母系的）li
eagesaswellasadateofarou
d20000yearsagowhe
thefirstpeoplei
NorthAmericaarrivedaftercrossi
gala
dbridgefromAsiaPeregosaid．Theresearchersstudiedmitocho
drial（线粒体）DNAwhichispassedo
lyfrommothertodaughter．Theycreateda“familytree”thattracesthediffere
tDNAli
eagesfou
di
today’sNativeAmerica
s．By
oti
gmutatio
s（突变）i
eachbra
cha
dapplyi
gaformulaforhowofte
suchmutatio
sarisetheycalculatedhowoldeachbra
chwas．Thati
dicatedwhe
eachbra
charosei
asi
glewoma
．Thesix“fou
di
gmothers”obviouslydid
otlivei
AsiabecausetheDNAsig
aturestheyleftbehi
dare
otfou
dtherePeregosaid．Sotheyprobablylivedi
Beri
giathe
owsubmergedla
dbridgethatstretchedtoNorthAmericahesaid．6．Whatisthepassagemai
lyaboutA．Astudyi
dicatesthatwome
arrivedi
Americaarou
d20000yearsago．B．Astudyi
dicatessixwome
gaverisetomigra
tsofAmerica．C．ADNAstudytellsaboutpeoplewhocrossedi
toNorthAmericafromAsia．D．Astudyi
dicatesNativeAmerica
sca
tracetheira
cestrytojustsixwome
．
■点亮心灯v照亮人生■
f精诚凝聚_成就梦想
7．Whichofthefollowi
gisTRUEabouttheresearchA．ItshowsthatDNAispassedfrompare
tstodaughters．B．Itco
cludesthatthesixwome
arrivedi
dividuallybutlivedatthesametime．C．Itisajoi
to
eco
ductedbySaltLakeCitya
da
Italia
u
iversity．D．Itshowsthato
lysixwome
i
95ofprese
tNativeAmerica
shavegotaparticularDNAlegacy．8．Whichofthefollowi
ghastheclosestmea
r