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
Here in the United States, before agricultural activities destroyed the natural balance, there were great migrations of Rocky Mo
Here in the United States, before agricultural activities destroyed the natural balance, there were great migrations of Rocky Mo
admin
2013-10-17
74
问题
Here in the United States, before agricultural activities destroyed the natural balance, there were great migrations of Rocky Mountain locusts (Melanoplus spretus). Great migrating hordes of these insects once darkened the skies on the plains east of the Rockies where crops were often destroyed; the worst years were those from 1874 to 1877. One of these migrating swarms was estimated to contain 124 billion locusts. During another migration in Nebraska it was estimated that the swarm of locusts averaged half a mile high and was 100 miles wide and 300 miles long. Usually, these swarms take off from the ground against the wind, but, once airborne, they turn and fly with it. Warm convection (对流) currents help to lift them, often to great heights. During the great locust plagues the situation in Nebraska became so serious that the original state constitution had to be rewritten to take care of the economic problems. The new document was known as "The Grasshopper Constitution". It is now believed that these locusts were a migratory form or phase of the lesser migratory locust, which is still common there. In this respect, the North American migratory locusts resemble their African relatives. In both regions the migratory forms arise as a result of crowding and climatic factors. Migratory forms are apparently natural adaptations which bring about dispersal when locust populations become too crowded.
Fortunately for our farmers, the migratory form—the so called spretus species—no longer seems to occur regularly, although there was a serious outbreak as late as 1938 in midwestern United States and Canada. Actually, there is no reason why the destructive migratory form might not again appear if circumstances should become favorable.
The passage supports which of the following conclusions?
选项
A、The outbreak of locusts in 1938 was more serious than any other in history.
B、Nebraska farmers had no locust problems in the years 1874—1877.
C、There is a possibility that crops in the Unite States might be destroyed by locusts in the future.
D、There is a chance that African migratory locusts may make their way to the United States.
答案
C
解析
本题为推断题。文中最后一句说:“事实上,如果环境变得对蝗虫有利,没有理由说,毁灭性的蝗虫迁徙不会再出现。”由此我们可以推断出这样一种可能:美国的农作物将来还会受到蝗虫的破坏。所以正确答案为C。本题亦可通过排除法找到答案。文中倒数第二句中说:“虽然在1938年美国的中西部和加拿大有一次严重的蝗灾爆发。”可见,文中并未说这次爆发的蝗灾比历史上任何一次都严重,故A可排除。文中第二句说“蝗灾造成最严重危害的时期是1874年至1877年”,但并没有提此期间内布拉斯加州的农民没有蝗灾问题,由此B可排除。文中第十句说:“在这一点上,北美的迁徙蝗虫与它们的非洲同类有相似之处。”文中并未提及或暗示非洲的迁徙蝗虫会迁徙到美国,故选项D可排除。
转载请注明原文地址:https://kaotiyun.com/show/h8XO777K
0
在职攻硕英语联考
相关试题推荐
Mostworthwhilecareersrequiresomekindofspecializedtraining.Ideally,therefore,thechoiceofa(n)【C1】______shouldbemad
Duringrecentyearswehaveheardmuchabout"race":howthisracedoescertainthingsandthatracebelievescertainthingsand
Duringrecentyearswehaveheardmuchabout"race":howthisracedoescertainthingsandthatracebelievescertainthingsand
Duringrecentyearswehaveheardmuchabout"race":howthisracedoescertainthingsandthatracebelievescertainthingsand
Forlaymenethnologyisprobablythemostinterestingofthebiologicalsciencesfortheveryreasonthatitconcernsanimalsin
Foranyonewhoisreallyconcernedaboutkeepingtheirthoughtsprivatethereisonlyonereliabletechnology:writewithapen
Heknewthathewouldbepunishedseverelybecauseofhisseriouserror.Thereforehe______awaythedaybeforeyesterday.
Thelawisagreatmassofrules,showingwhenandhowfaramanisliabletobepunished,ortobemadetohandovermoneyorp
随机试题
A.协同作用B.拮抗作用C.相加作用D.独立作用E.混合作用当两种化学物质同时进入机体产生联合作用为各单项化学物质毒性总和
规模较大的工程施工招标项目可以通过考察投标资格申请人()工程施工规模、数量,了解投标人可以调动的剩余施工资源和能力。
不能将企业支付的外购存货的增值税记入存货的采购成本。()
论抵押权的标的。
如果“只有你去比赛,我才去观战”为真命题,则下列为假命题的一项是()。
下列选项中属于辩证法观点的是()。
RemoteSensingSatellite
下面对于友元函数描述正确的是()。
设萨3,b=5,则以下表达式值为真的是()。
Youwillhearfivedifferentpeoplewhohaveallbeeninterviewedforjobswithalargeinternationalcompanywhichisgoingto
最新回复
(
0
)