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、There are 250 million plants eaten by insects. B、There are fewer plants than 250 million years ago. C、They have their way of g
A、There are 250 million plants eaten by insects. B、There are fewer plants than 250 million years ago. C、They have their way of g
admin
2016-08-25
29
问题
Scientists have observed that plants themselves produce many poisonous chemicals for defense against insects. But insects have developed ways of dealing with them and, in fact, have been eating plants for about 250 million years. Now insects are using these same mechanisms to deal with man-made poisons—insecticide. This is why resistance of insects to insecticide has developed so rapidly. What should be done? Scientists studying the problem suggest that farmers use less insecticide. At the moment, farmers regularly spray crops as a precaution against problems that are caused by large numbers of pests. They should, instead, spray only where pests have actually been seen. Secondly, farmers could use a combination of two or three insecticide at once. To survive, the insects would need to become resistant to two or more poisons at the same time. The most surprising suggestion, perhaps, is that, at certain times of the year, farmers should actually try to attract new insects onto the crops they are trying to protect The new insects will mate with those which survived from a certain kind of insecticide and will lessen the latter’s resistance to it.
Scientists hope that these and other measures will postpone the day when farmers and scientists will have to stand by while new super bugs which may be resistant to all our poisons invade our farms and devour our crops.
19 What does the speaker say about plants?
20 What is mentioned as one of the suggestions raised by scientists?
21 What is the most surprising suggestion scientists give?
选项
A、There are 250 million plants eaten by insects.
B、There are fewer plants than 250 million years ago.
C、They have their way of guarding against insects.
D、They have a better immune system than before.
答案
C
解析
短文开头就说到,科学家发现植物自身可以产生许多有害的化学物质来抵御昆虫的侵害,即植物自有抵制昆虫侵害的方法,C与此含义相符,故正确。
转载请注明原文地址:https://kaotiyun.com/show/pQY7777K
0
大学英语四级
相关试题推荐
InasurveyconductedbyresearchfirmHarrisInteractive,71%ofAmericanssaidthatspendingextramoneyontravelduringthe
Thesedays,peoplewhodo【C1】______workoftenreceivefarmoremoneythanpeoplewhoworkinoffices.Peoplewhoworkinoffices
IdentityTheftA)Identitytheftandidentityfraudaretermsusedtorefertoalltypesofcrimeinwhichsomeonewrongfullyobt
Writeashortessaybasedonthepieturebelow.YoushouldstartyouressaywithabriefaccountofStudyinginCollegesorthro
A、Hewouldratherdecidelater.B、Thewomancansetthemeetingdate.C、Hewilldecideanotherplacetomeet.D、Thewomancanco
A、Heprefersstayingathomebecausethebusistoolate.B、Heprefersstayingathomebecausehedoesn’tliketotravel.C、Hep
A、Hehasalreadyarrived.B、Heisoftenlate.C、Hehasgottenawrongaddress.D、Heprobablydidn’tgetthemessage.B事实状况题。男士说D
A、Heisofferedanewjob.B、Heisgrantedtoleaveforonemonth.C、Heisfiredbythecompany.D、Heisdismissedforhispoor
"Don’ttakemanyEnglishcourses;theywon’thelpyougetadecentjob.""Signupformanagementclasses,soyou’llbereadyto
TeachersandparentsnormallycallattentiontothepictureswhentheyreadstorybookstopreschoolchildrenButastudysuggest
随机试题
意识能动作用最突出的表现是()
中等卫校毕业生林某,在乡卫生院工作,2000年取得执业助理医师执业证书。他要参加执业医师资格考试,根据《执业医师法》规定,取得执业助理医师执业证书后,在医疗机构中工作满
硝苯地平治疗高血压过程中,患者出现踝部水肿,发生原因是
出料加工货物未按海关允许期限复运进境的,海关按照一般进出口货物办理。()
长江公司为增值税一般纳税人,适用的增值税税率为17%,长江公司相关交易或事项有关资料如下: (1)长江公司于2010年9月30日向黄河公司销售一批产品。应收黄河公司的货款为9360万元(含增值税)。黄河公司于当日开出一张期限为6个月,票面利率为8%的商
2007年度,甲公司为推销其产品,拟在电视上作产品宣传广告,为此特聘请某广告公司为其制作产品广告,共发生广告制作费200万元,甲公司要求其子公司B公司为其承担200万元的广告费支出,B公司将这笔广告费直接一次支付给了广告公司。则甲公司在2007年度应做的会
孔子是儒家学派的创始人,也是教师的楷模。他在教学中注重培养人内在素养和外在表现的统一,以德才兼备、温文尔雅的君子作为其教育目标。下列选项中,展现德才兼备的教学思想的是()。
在Access中,如果变量定义在模块的过程内部,当过程代码执行时才可见,则这种变量的作用域为()
ThereasonsgivenbelowaboutthepopularityofE-mailcanbefoundinthepassageexcept______.Whatwillhappentofax,land
Whatdoesthewomanmeanby"giveyouabuzz"?
最新回复
(
0
)