練習(xí)材料

Lesson 20-2 Snake poison

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 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 is called neurotoxic.

/?l?s?n/ 20-2 /sne?k/ /?p??z?n/

?

/?n/ /f?kt/, /?t/ /w?d/ /bi/ /?n/ /??s?st?ns/ /tu/ /?l/ /?kɑrn??v?rz/ /eo?/ /?t/ /w?d/ /bi/ /?/ /tu/-/??d/ /?w?p?n/ /w?n/ /ee?/ /f?t/ /i?/ /??e?r/. /b?t/, /?v/ /e?/ /?v?rt??bre?ts/, /??npr??d?kt?b?l/ /?ne???r/ /s??l?kt?d/ /?o?nli/ /sne?ks/ (/?nd/ /w?n/ /?l?z?rd/). /w?n/ /?w?nd?rz/ /??lso?/ /wa?/ /?ne???r/, /w?e/ /s?m/ /sne?ks/, /k?n?kɑkt?d/ /?p??z?n/ /?v/ /s??/ /?k?strim/ /?po?t?nsi/.

/?n/ /e?/ /k?n?v?r??n/ /?v/ /s??la?v?/ /??ntu/ /?p??z?n/, /w?n/ /ma?t/ /s??po?z/ /e?t/ /?/ /f?kst/ /?prɑ?s?s/ /t?k/ /ple?s/. /?t/ /d?d/ /nɑt/; /s?m/ /sne?ks/ /?m?nj??f?k??r/ /?/ /?p??z?n/ /?d?f?r?nt/ /?n/ /??v?ri/ /r??sp?kt/ /fr?m/ /e?t/ /?v/ /??e?rz/, /?z/ /?d?f?r?nt/ /?z/ /?ɑrs?n?k/ /?z/ /fr?m/ /?str?k?na?n/, /?nd/ /?h?v??/ /?d?f?r?nt/ /??f?kts/. /w?n/ /?p??z?n/ /?kts/ /ɑn/ /e?/ /n?rvz/, /ei/ /??e?r/ /ɑn/ /e?/ /bl?d/.

/e?/ /?me?k?rz/ /?v/ /e?/ /n?rv/ /?p??z?n/ /?n?klud/ /e?/ /?mɑmb?z/ /?nd/ /e?/ /?ko?br?z/ /?nd/ /e?r/ /?v?n?m/ /?z/ /k?ld/ neurotoxic.