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
How it came about that snakes manufactured poison is a mystery. Over me periods their saliva, a mild, digestive juice like our o
How it came about that snakes manufactured poison is a mystery. Over me periods their saliva, a mild, digestive juice like our o
admin
2015-01-28
20
问题
How it came about that snakes manufactured poison is a mystery. Over me periods their saliva, a mild, digestive juice like our own, was converted into a poison that defies analysis even today. It was not forced upon them by the survival competition: they could have caught and lived on prey without using poison just as the thousands of non-poisonous snakes still do. Poison to a snake is merely a luxury: it enables it to get its food with very little effort, no more effort than one bite. And why only snakes? Cats, for instance, would be greatly helped: no running fights with large, fierce rats or struggles with grown rabbits—just a bite and no more effort needed. In fact, it would be an assistance to all the carnivores—though it would be a two-edged weapon when they fought each other. But, of the vertebrates, unpredictable Nature selected only snakes(and one lizard). One wonders also why Nature, with some snakes concocted poison of such extreme power.
In the conversion of saliva into poison one might suppose that a fixed process took place. It did not: some snakes manufactured a poison different in every respect from that of others, as different as arsenic is from strychnine, and having different effects. One poison acts on the nerves, the other on the blood.
The makers of the nerve poison include the Mambas and the Cobras and their venom(毒液)is called neurotoxic(毒害神经毒液). Vipers(Adders)and Rattlesnakes manufacture the blood poison, which is known as haemolytic(溶血毒液). Both poisons are unpleasant, but by far the more unpleasant is the blood poison. It is said that the nerve poison is the more primitive of the two, mat the blood poison is, so to speak, a newer product from an improved formula. Be that as it may, the nerve poison does its business with man far more quickly than the blood poison. This, however, means nothing. Snakes do not acquire their poison for use against man but for use against prey such as rats and mice, and the effect on these of viperine poison is almost immediate.
According to the text snake poison______.
选项
A、can be analyzed
B、can not be analyzed
C、is converted in a similar way
D、is converted in an easy way
答案
B
解析
由第一段第二句可知蛇毒是不能被人们所认识和分析的。
转载请注明原文地址:https://jikaoti.com/ti/C9WsFFFM
本试题收录于:
公共英语三级笔试题库公共英语(PETS)分类
0
公共英语三级笔试
公共英语(PETS)
相关试题推荐
AreyoureadyforyourAvrilLavigne(Americanpopsinger)mobilephone?Cellphonecompaniesaredevelopinganewwirelessphone
Accordingtothewoman,whatgovernstheclotheswewear?
Whodoyouthinkarethetwospeakersintheconversation?
Howdoesthemanseemtofeelaboutdrivingfromhishometohiswork?
OneofthemoststrikingthingsaboutAmericansisthattheyseemofexpectingeveryonetolikethem【C1】______.theygo.America
OneofthemoststrikingthingsaboutAmericansisthattheyseemofexpectingeveryonetolikethem【C1】______.theygo.America
Readthefollowingparagraphsinwhichfivepeopletalkaboutsmoking.Forquestions61to65,matchthenameofeachspeaker(6
Thereisanewtypeofsmalladvertisementbecomingincreasinglycommonmnewspaperclassifiedcolumns.Itissometimesplaceda
Kiteflyingisthesportofsendingupintotheair,bymeansofthewind,alightframecoveredwithpaper,plasticorcloth.T
Kiteflyingisthesportofsendingupintotheair,bymeansofthewind,alightframecoveredwithpaper,plasticorcloth.T
随机试题
语言混合的形式有()
患者女,57岁,三个月前发烧,“发现右肺阴影”,治疗经过不详。CΥ扫描示右上肺胸膜下多房性空洞,部分空洞内可见小液平,病变周围散在小斑片状病灶,相邻胸膜增厚,最可能的诊断为:
苯作业职工定期健康检查间隔时间(年)
乳腺摄影X线机使用的自动曝光控制形式有
医学伦理学的特征之一是
学习动机的激发是指使潜在的学习动机转化为学习的行动。()
如何培养幼儿的创造性?
A、 B、 C、 D、 B
设A=有三个线性无关的特征向量,求a及An.
下列数据结构中,不能采用顺序存储结构的是()。
最新回复
(
0
)