练习材料：
Lesson 20-2 Snake poison
In fact, it wouldbe an assistance to all carnivores though it would be a two-edged weapon whenthey fought each other. But, of the vertebrates, unpredictable Nature selectedonly snakes (and one lizard). One wonders also why Nature, with some snakes,concocted poison of such extreme potency.
In the conversionof saliva into poison, one might suppose that a fixed process took place. Itdid not; some snakes manufacture a poison different in every respect from thatof others, as different as arsenic is from strychnine, and having differenteffects. One poison acts on the nerves, the other on the blood.
The makers of thenerve poison include the mambas and the cobras and their venom is calledneurotoxic.
sneɪk ˈpɔɪzn
ɪn fækt, ɪt wʊd
biː ən əˈsɪstəns tuː ɔːl ˈkɑːnɪvɔːz ðəʊ ɪt wʊd biː ə ˈtuːˈɛʤd ˈwɛpən wɛn ðeɪ fɔːt iːʧ ˈʌðə. bʌt, ɒvðə ˈvɜːtɪbrɪts, ˌʌnprɪˈdɪktəbl ˈneɪʧə sɪˈlɛktɪd ˈəʊnli sneɪks (ænd wʌn ˈlɪzəd).wʌn ˈwʌndəz ˈɔːlsəʊ waɪ ˈneɪʧə, wɪð sʌm sneɪks, kənˈkɒktɪd ˈpɔɪzn ɒv sʌʧ ɪksˈtriːmˈpəʊtənsi.
ɪn ðə kənˈvɜːʃən ɒv
səˈlaɪvə ˈɪntuː ˈpɔɪzn, wʌn maɪt səˈpəʊz ðæt ə fɪkst ˈprəʊsɛs tʊk pleɪs. ɪt dɪd
nɒt; sʌm sneɪks ˌmænjʊˈfækʧər ə ˈpɔɪzn ˈdɪfrənt ɪn ˈɛvri rɪsˈpɛkt frɒm ðæt ɒv ˈʌðəz,
æz ˈdɪfrənt æz ˈɑːsnɪk ɪz frɒm ˈstrɪkniːn, ænd ˈhævɪŋ ˈdɪfrəntɪˈfɛkts. wʌn ˈpɔɪzn ækts ɒn ðə nɜːvz, ði ˈʌðər ɒn ðə blʌd.
ðə ˈmeɪkəz ɒv ðə nɜːvˈpɔɪzn ɪnˈkluːd ðə mambas ænd ðə ˈkəʊbrəz ænd ðeə ˈvɛnəm ɪz kɔːld neurotoxic.
任务配置：L0 + L4
知识笔记：
单词：1、carnivore：肉食动物，2、vertebrate：脊椎动物，3、unpredictable：不可预料的，变幻莫测，4、lizard：蜥蜴，5、potency：效力，6、arsenic：砷，砒，7、strychnine：士的宁，8、mambas：曼巴，9、cobras：眼镜蛇，10、venom：毒液，毒汁，毒物，11、neurotoxic：神经毒性
音标：
练习感悟：这又是今天的第二篇，读一篇都好吃力了，要再补一篇，确实非常辛苦
