首页
登录
职称英语
Here in the United States, before agricultural activities destroyed the natu
Here in the United States, before agricultural activities destroyed the natu
游客
2025-03-19
30
管理
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. [br] 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://tihaiku.com/zcyy/4003614.html
相关试题推荐
Don’tforgetto______yourletterbeforeyoumailit.A、fastenB、shutC、sealD、sti
Howoftenhaveyouqueuedfor______seemslikehoursatthebookingofficebefore
EventhoughIhavebeentoherapartmentseveraltimesbefore,Istilldon’trem
SpeakerA:Thelightsareaboutoff,butI’dliketobuysomeice-creambeforet
Beforethesummerof2000,the54-year-oldJohnHaughomcouldaccomplishjus
Beforethesummerof2000,the54-year-oldJohnHaughomcouldaccomplishjus
Beforethesummerof2000,the54-year-oldJohnHaughomcouldaccomplishjus
TheUnitedStatesiswell-knownforitsnetworkofmajorhighwaysdesignedt
TheUnitedStatesiswell-knownforitsnetworkofmajorhighwaysdesignedt
TheUnitedStatesiswell-knownforitsnetworkofmajorhighwaysdesignedt
随机试题
Mother’sDayisaday【11】tohonormothers.ItisobservedintheU.S.onthe
[originaltext]M.Hello.MayIspeaktoMr.George?W:Mr.Georgeisnotin,cou
MarkTwain’sgoodeducationismainlythefoundationforhisworks.[br]Wedon’
下列文书的内容不具有前瞻性、预测性的是()。A.总结 B.计划 C.调查报
(2017年)2016年某公司给自有员工实际发放合理工资总额为1000万元;公司
运用基准地价系数修正法评估宗地地价时,在对基准地价修正的过程中,需要利用的主要修
2009年,某省全年粮食作物播种面积253.85万公顷,比上年增长1.5%
在环境适宜时能发育成细菌繁殖体的是A.病毒 B.螺旋体 C.细胞壁 D.芽
共用题干 某企业开发出一种新产品,单位成本为1000元。根据以上资料,回答下列
银行承兑汇票的承兑银行,应当按照票面金额向出票人收取()的手续费。A:千分之一
最新回复
(
0
)