新概念英语第四册第20课课后习题及答案

　　Unit 20 BCADC CCBDB CA

　　新概念英语第4册课后习题:

　　Multiple choice questions 多项选择题

　　Choose the correct answers to the following questions.

　　Comprehension 理解

　　1 One of these statements is true.Which one?

　　a.Snakes need poison to digest their food.

　　b.Snakes can feed on other animals without the use of poison.

　　c.Non-poisonous snakes find survival more difficult than poisonous ones.

　　d.All snakes are capable of manufacturing poison.

　　2 The possession of poison in the saliva makes hunting ____.

　　a.easy for all carnivores

　　b.a two-edged weapon when carnivores fight each other

　　c.almost effortless for snakes

　　d.unpredictable, as Nature intended

　　3 The poison that acts on the blood ____.

　　a.acts less rapidly than nerve poison

　　b.doesn't affect the victim as badly as nervepoison

　　c.is made by snakes like mambas and cobras

　　d.was probably the first of the two kinds of poisonto be developed

　　4 Human beings ____.

　　a.can't compare with prey such as rats and mice

　　b.respond to all snake poisons in the same way

　　c.are likely to survive nerve poison but not blood poison

　　d.are not the intended victims of snake poison

　　Structure 句型

　　5 They ____ have been able to catch and live on prey without using poison.(1.3)

　　a.might

　　b.should

　　c.would

　　d.must

　　6 They could have caught and lived on prey without ____ poison.(1.3)

　　a.to use

　　b.use

　　c.the use of

　　d.have used

　　7 For ____ snakes, poison is merely a luxury.(1.4)

　　a.these

　　b.a

　　c.-

　　d.an

　　8 Blood poison is the more unpleasant ____.(1.15)

　　a.of them all

　　b.of the two

　　c.in the world

　　d.among them both

　　Vocabulary 词汇

　　9 Saliva is a natural ____.(11.1-2)

　　a.oil in the body

　　b.snake-poison

　　c.digestive process

　　d.body fluid

　　10 Poison would be ____ to all carnivores.(1.7)

　　a.an asset

　　b.a help

　　c.a necessity

　　d.a disadvantage

　　11 Arsenic and strychnine ____ us in different ways.(1.11.11-12)

　　a.effect

　　b.result

　　c.affect

　　d.cause

　　12 The nerve poison is thought to be ____(11.15-16)

　　a.less highly developed

　　b.more potent

　　c.more recent

　　d.less complicated新概念英语