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
A、Collect ash tree seeds for experiment. B、Preserve the healthy ash tree seeds. C、Set up a new seed bank for research. D、Develop
A、Collect ash tree seeds for experiment. B、Preserve the healthy ash tree seeds. C、Set up a new seed bank for research. D、Develop
admin
2018-07-27
56
问题
A beetle invasion in the United States has killed at least twenty million ash trees. The invasion of the emerald ash borer was first discovered near Detroit, Michigan, in 2002. Experts believe the small green insects arrived in the 1990’s in shipments of goods from China.
[16] The emerald ash borer has destroyed trees in the Midwest and as far East in the United States as Maryland. [17] The insects have also spread as far north as Ontario, Canada.
Ash trees can resist many diseases. But they cannot resist the emerald ash borer. [18-1] It lays eggs on the bark.The young larva drill into and feed on the inner bark. This harms the ability of the tree to transport water and nutrition.
In some places, farmers are using “detection trees”. They have an area where bark has been cut away. The area circles the tree. [18-2] The process weakens the tree. It makes them easier targets for borers, and shows if the insects are nearby.
Efforts to stop the spread of the emerald ash borer include cutting down affected trees. There are worries that the ash tree might disappear unless the invasion is controlled. To prepare for such a possibility, a government laboratory is asking people to send in the seeds from ash trees. [19] It examines and X-rays the seeds to make sure there are no living borer fertilized eggs.Only the best seeds are remained and then sent for storage in a seed bank. There, they are dried and frozen. Should the seeds ever be needed, the hope is that scientists might someday develop an ash tree that could resist the little green attackers.
1.What’s the speaker mainly talking about?
2.How far do the insects spread northward?
3.Why is part of the bark cut away?
4.What is the government laboratory trying to do?
选项
A、Collect ash tree seeds for experiment.
B、Preserve the healthy ash tree seeds.
C、Set up a new seed bank for research.
D、Develop a new breed of ash tree.
答案
B
解析
转载请注明原文地址:https://kaotiyun.com/show/9EH7777K
0
大学英语六级
相关试题推荐
A、Toopenastudio.B、Tokeephealthy.C、Toreleasepressure.D、Tobecomeaninstructor.C本题问的是Georgia练习瑜伽的最初目的是什么。短文末尾提到,Georgi
A、Thesummervacationiscoming.B、Sheisgoingtohaveajobinterview.C、Shewillgotohergrandma’s.D、She’sjustgotheral
A、Universitiesdon’tpaymuchattentiontoacademicachievement.B、Professorsassigntoomuchworktostudentsinashorttime.
A、Togiveuphispresentjob.B、Togetmoretraining.C、Toworkforawebhostingcompany.D、Toseizeopportunitiesofpromotion
A、Punishingstudentswhodamageschoolproperty.B、Rewardingschoolsthathavedecreasedthedestruction.C、Promotingteachersw
Marketplaceorpeer-to-peer(P2P)lendingmatchesborrowersandlendersonlow-costonlineplatforms.Byskirtingbanks,P2Plendi
Reebokexecutivesdonotliketoheartheirstylishathleticshoescalled"footwearforyuppies(雅皮士,少壮高薪职业人士)".Theycontendtha
A、Shegotaglimpseofthequeen.B、ShehasbeentoLondonforrelax.C、ShehadawonderfultimeinLondon.D、Shesawmanyoldc
随机试题
DSS与MIS比较,其特点是
一淋巴瘤患者双侧颈部淋巴结肿大,胸、腹部CT检查提示左肺内有一直径3.5cm大小的结节影,无发热、盗汗及体重减轻,临床分期为_________期。
反映小儿体格发育状况最重要的指标是()
A.1周以内B.2周以内C.2周~2个月D.2个月以上E.半年以上迁延性腹泻病程为
男,25岁。头外伤昏迷5分钟后清醒,送医院途中再度陷入昏迷,伴呕吐。体检:浅昏迷,双侧瞳孔等大等圆,对光反射迟钝,左侧肢体肌力Ⅳ级,巴宾斯基征阳性。最可能的诊断是
工程量清单计价是指依据工程量清单和(),由市场竞争形成工程造价的计价模式与方法。
工程项目进度计划中资源优化的目的是为了寻求()。
《十一五规划纲要》主要()。
下列心理现象中,属于学习的是()。
生态系统是指由生物群落与无机环境构成的统一整体。生态系统的范围可大可小,相互交错,最大的生态系统是生物圈。生态系统是开放系统,为了维系自身的稳定,生态系统需要不断输入能量,否则就有崩溃的危险。下列各项中,构成生态系统的是()。
最新回复
(
0
)