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
外语
An eagle wheels overhead against a crystalline blue sky, Martin Flanagan walks toward a grove of towering cottonwood trees besid
An eagle wheels overhead against a crystalline blue sky, Martin Flanagan walks toward a grove of towering cottonwood trees besid
admin
2015-01-30
45
问题
An eagle wheels overhead against a crystalline blue sky, Martin Flanagan walks toward a grove of towering cottonwood trees beside the Yellowstone River, which is the color of chocolate milk due to the spring rain.
As Mr. Flanagan leaves the glaring sun of the prairie and enters the shady grove, his eyes search for a specific tree. As he reaches a narrow-leaf cottonwood, a towering giant, he cranes his neck to look at the top. "This is the one I plan to nominate for state champion," he says, petting the bark with his hand. "It’s beautiful isn’t it?"
When Europeans first came to North America, one of the largest primeval forests in the world covered much of the continent. Experts say a squirrel could have traveled from the Atlantic coast to the Mississippi River without touching the ground. But only about 3 percent of America’s native old-growth forest remains, and many of the trees they hold are those that were not big enough to attract a logger’s eyes. The result is a generation of trees that barely resemble the native forests that once covered the country.
That makes some scientists suspect that the surviving forests have lost much of their genetic quality, the molecular muscle that made them dominate the landscape. When the loggers swept through, these scientists say, only poor specimens were left to reproduce. Other researchers wonder whether environmental factors or just plain luck may explain a good part of the supertrees’ success.
To answer those questions, the mightiest trees of their types, or genetically identical offspring, must be preserved for study, and that is what is being done by a handful of enthusiasts, including Mr. Flanagan and David Milarch, a nurseryman from Copemish, Mich. They are searching out the largest tree of each species and taking cuttings of new growth to make copies of genetic clones of the giants. With tissue culture and grafting, they have reproduced 52 of the 827 living giants and are planning the offspring in what they call "living libraries." More than 20,000 offspring have been planted.
Directions: Complete the following sentences with information given in the passage in a maximum of 10 words for each blank.
People are doing researches on the largest tree of each species and taking cuttings of new growth to______.
选项
答案
make copies of genetic clones of the giants
解析
转载请注明原文地址:https://kaotiyun.com/show/2KVK777K
本试题收录于:
C类竞赛(非英语专业本科)题库大学生英语竞赛(NECCS)分类
0
C类竞赛(非英语专业本科)
大学生英语竞赛(NECCS)
相关试题推荐
(1)Faster,cheaper,better—technologyisonefieldmanypeoplerelyupontoofferavisionofabrighterfuture.Butasthe202
A、Paymoreattentiontogrades.B、Trytojudgestudentsfairly.C、Focusonstudents’efforts.D、Workhardtoavoidquitting.C由原
AllthefollowingsentenceshaveanappositiveEXCEPT________.
Wedonotusuallygivemuchthoughttohowthethingsthatsurroundusinoureverydaylivesarecreated.Everythingweuse—from
LOOKONTHEBRIGHTSIDEDoyoueverwishyouweremoreoptimistic,someonewhoalways【16】ex______tobesuccessful?Havings
InBritain,therearetwooccasionseachyearwhenpeopleusuallyreceivepresents:onChristmasDayandontheirbirthdays.In
Industrialpsychologyistheapplicationofvariouspsychologicaltechniquestotheselectionandtrainingofindustrialworkers
Howlongwillittakefornewforeststogrowback?
Itissaidthatwithmoreforests______hugequantitiesofgoodeartharebeingwashedaway.
TheOlympicmottoismadeupofthreewords:FASTER—HIGHER—STRONGER.ThemottocanbecomparedtotheOlympiccreed(宗旨)whichs
随机试题
Forty-threepercentofAmericanssaytheyaretootiredtofunction.So,somemornings,youmighteven【C1】________stayinginbed
有利于促进低成本战略目标实现的组织是()
下列治疗热厥实证的组穴是:
下列哪一类神经纤维属于肾上腺素能神经
A.不寐,性情急躁易怒,口苦B.不寐,头重,痰多胸闷,苔黄腻C.心烦不寐,头晕,耳鸣,腰酸梦遗D.多梦易醒,肢倦神疲,面色少华E.不寐多梦,易于惊醒,胆怯心悸,遇事善惊
A55%B8%C38%D37%E7%接待投诉者时的举止行为要点、语调表达占
工业企业其资金运动包括各特定对象()。
纳税人进口应税消费品,实行从价定率办法征收时,海关确定的组成计税价格=( )。
社会主义初级阶段的基本经济制度是()。
A、Beforebreakfast.B、Latemorning.C、Mid-afternoon.D、Lateevening.CThewomansaid,“Itcouldbethattherearen’tenoughpeopl
最新回复
(
0
)