新概念英语教材

　　新概念英语第四册教材讲了哪些内容？出国留学网英语考试频道为大家整理提供“新概念英语第四册教材之Snake poison”。祝考生们顺利通过英语考试!

　　Snake poison

　　蛇毒

　　First listen and then answer the following question.

　　听录音，然后回答以下问题。

　　What are the two different ways in which snake poison acts?

　　How it came about that snakes manufactured poison is a mystery. Over the 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 tussles with grown rabbits -- just a bite and no more effort needed. In fact, it would be an assistance to all 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 potency.

　　In the conversion of saliva into poison, one might suppose that a fixed process took place. It did not; some snakes manufacture a poi...

　　新概念英语第四册课文讲了哪些具体内容?出国留学网英语考试频道为大家整理提供“新概念英语第四册课文精讲：The great escape”。祝考生们顺利通过英语考试!

　　The great escape

　　大逃亡

　　First listen and then answer the following quesion.

　　听录音，然后回答以下问题。

　　What is one of the features of modern camping where nationality is concerned?

　　Economy is one powerful motive for camping, since after the initial outlay upon equipment, or through hiring it, the total expense can be far less than the cost of hotels. But, contrary to a popular assumption, it is far from being the only one, or even the greatest. The man who manoeuvres carelessly into his 20 pounds' worth of space at one of Europe's myriad permanent sites may find himself bumping a Bentley. More likely, Ford Escort will be hub to hub with Renault or Mercedes, but rarely with bicycles made for two.

　　That the equipment of modern camping becomes yearly more sophisticated is an entertaining paradox for the cynic, a brighter promise for the hopeful traveler who has sworn to get away from it all. It also provides and some student sociologist might care to base his thesis upon the phenomenon -- an escape of another kind. The modern traveller is often a man who dislikes the Splendide and the Bellavista, not because he cannot afford, or shuns their material comforts. but because he is afraid of them. Affluent he may be, but he is by no means s...