Lesson 20 Snake poison

歌曲 Lesson 20 Snake poison
歌手 英语听力
专辑 新概念英语(第四册)

歌词

[00:01.50] Lesson 20
[00:03.44] Snake poison
[00:11.03] What are the two different ways in which snake poison acts?
[00:17.22] How in came about that snakes manufactured poison is a mystery.
[00:22.09] Over the periods their saliva, a mild, digestive juice like our own, was converted into a poison that defies analysis even today.
[00:32.88] It was not forced upon them by the survival competition;
[00:36.57] they could have caught and lived on prey without using poison, just as the thousands of non-poisonous snakes still do.
[00:44.90] Poison to a snake is merely a luxury;
[00:48.40] it enables it to get its food with very little effort, no more effort than one bite.
[00:55.01] And why only snakes?
[00:57.76] Cats, for instance, would be greatly helped;
[01:00.78] no running fights with large, fierce rats or tussles with grown rabbits--just a bite and no more effort needed.
[01:09.71] In fact, it would be an assistance to all carnivores though it would be a two-edged weapon when they fought each other.
[01:17.73] But, of the vertebrates unpredictable Nature selected only snakes (and one lizard).
[01:24.77] One wonders also why Nature, with some snakes concocted poison of such extreme potency.
[01:32.94] In the conversion of saliva into poison, one might suppose that a fixed process took place. It did not;
[01:40.81] some snakes manufactured a poison different in every respect from that of others, as different as arsenic is from strychnine, and having different effects.
[01:52.16] One poison acts on the nerves, the other on the blood.
[01:57.15] The makers of the nerve poison include the mambas and the cobras and their venom is called neurotoxic.
[02:05.87] Vipers (adders) and rattlesnakes manufacture the blood poison, which is known as haemolytic.
[02:14.47] Both poisons are unpleasant, but by far the more unpleasant is the blood poison.
[02:21.37] It is said that the nerve poison is the more primitive of the two, that the blood poison is, so to speak, a newer product from an improved formula.
[02:31.94] Be that as it may, the nerve poison does its business with man far more quickly than the blood poison.
[02:39.98] This, however, means nothing.
[02:42.19] Snakes did not acquire their poison for use against man but for use against prey such as rats and mice, and the effects on these of viperine poison is almost immediate.

歌词大意

[00:01.50] dì 20 jié
[00:03.44] shé dú
[00:11.03] shé dú de liǎng zhǒng bù tóng de zuò yòng shì shén me?
[00:17.22] shé shì zěn yàng chǎn shēng dú yè de, zhè shì yí gè mí
[00:22.09] shé de tuò yè běn lái hé wǒ men rén de xiāo huà yè yí yàng róu hé, dàn jīng guò màn cháng de shí jiān, yǎn biàn chéng le jīn tiān réng wú fǎ fēn xī qīng chǔ de dú yè
[00:32.88] dú yè bú shì shēng cún jìng zhēng qiáng jiā gěi tā men de
[00:36.57] tā men yě kě yǐ bù yòng dú yè bǔ zhuō dòng wù ér shēng cún, jiù xiàng jīn tiān chéng qiān shàng wàn de wú dú shé nà yàng
[00:44.90] dú yè duì dú shé lái shuō zhǐ bù guò shì yī zhǒng shū shì shēng cún de yōu yuè shǒu duàn
[00:48.40] tā shǐ shé bù yòng fèi duō dà lì qì jiù néng bǔ huò dào shí wù, qīng yǎo yī kǒu jí kě
[00:55.01] wèi shí me zhǐ yǒu shé cái yǒu dú yè ne
[00:57.76] pì rú shuō, rú guǒ māo yǒu dú yè, nà duì māo huì dà yǒu bāng zhù
[01:00.78] tā jiù bù bì zài hé yòu dà yòu xiōng de lǎo shǔ biān pǎo biān bó dòu le, yě bù bì zài hé dà tù zi niǔ dòu le
[01:09.71] yīn cǐ, rèn hé shí ròu dòng wù yǒu le dú yè, dōu néng cóng zhōng huò yì. bù guò, dāng tā men xiāng hù sī dǎ shí, dú yè jiù chéng le lì bì cān bàn de wǔ, kě yǐ shā sǐ duì fāng, yě kě yǐ bèi duì fāng de dú yè shā sǐ
[01:17.73] rán ér, zài jǐ zhuī dòng wù zhōng, dà zì rán shén mì mó cè dì zhǐ xuǎn zé le shé hái yǒu yī zhǒng xī yì
[01:24.77] rén men nòng bù qīng chǔ dà zì rán wèi shí me zài mǒu xiē shé de shēn shàng tiáo zhì chū rú cǐ gāo xiào de dú yè lái
[01:32.94] rén men kě néng rèn wéi, tuò yè zhuǎn biàn chéng dú yè, qí zhōng yǒu gù dìng de chéng xù. qí shí méi yǒu
[01:40.81] yǒu xiē shé chǎn shēng de dú yè yě zài gè fāng miàn yǔ lìng wài yī xiē dú shé chǎn shēng de dú yè bù tóng, jiù xiàng pī shuāng bù tóng yú mǎ qián zǐ jiǎn yí yàng
[01:52.16] bù tóng dú shé chǎn shēng de dú yè chǎn shēng de xiào guǒ bù tóng, yī zhǒng dú yè zuò yòng yú shén jīng, lìng yī zhǒng dú yè zuò yòng yú xuè yè
[01:57.15] chǎn shēng shén jīng dú yè de shé yǒu yī zhǒng fēi zhōu shù yǎn jìng shé hé yǎn jìng shé, tā men de dú yè chēng wéi shén jīng dú sù
[02:05.87] kuí shé fù shé hé xiǎng wěi shé chǎn shēng xuè yè dú sù, chēng wéi róng xuè xìng dú yè
[02:14.47] zhè liǎng zhǒng dú yè dōu hěn kě pà, dàn róng xuè xìng dú yè yóu qí lì hài
[02:21.37] jù shuō, shén jīng dú yè zài liǎng zhǒng dú yè zhōng shì jiào wéi yuán shǐ de yī zhǒng, ér róng xuè xìng dú yè, dǎ gè bǐ fāng shuō, shì gēn jù gǎi liáng pèi fāng shēng chǎn de yī zhǒng jiào xīn de chǎn pǐn
[02:31.94] bù guò, shén jīng dú là yè bǐ róng xuè xìng dú yè zài rén shēn shàng qǐ zuò yòng kuài dé duō
[02:39.98] dàn shì, zhè méi yǒu shén me guān xì
[02:42.19] yīn wèi shé yǒu dú yè bú shì yòng lái duì fù rén de, ér shì duì fù tā de liè wù, zhū rú shǔ lèi, dú yè duì zhèi xiē liè wù huì lì kè qǐ zuò yòng