试题与答案

鱼类氮代谢的终产物是氨,两栖类成体氮代谢的终产物是尿素,鸟类氮代谢的终产物主要是

题型:解答题

题目:

鱼类氮代谢的终产物是氨,两栖类成体氮代谢的终产物是尿素,鸟类氮代谢的终产物主要是尿酸.在鸡的胚胎发育过程中,最早几天氮代谢的终产物是氨,过几天变成了尿素,最后以尿酸代谢为主,这说明:

(1)鸡早期胚胎像______,过几天像______,最后才像______.

(2)从鸡胚胎氮代谢终产物的变化可以看出高等动物是由______进化而来,进化方向是______.

答案:

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Our tragedy today is a general and universal physical fear so long sustained by now that we can even bear it. There are no longer problems of the spirit. There is only the question: when will I be blown up Because of this, the young man or woman writing today has forgotten the problems of the human heart in conflict with itself which alone can make good writing because only that is worth writing about, worth the agony and sweat. He must learn them again. He must teach himself that the basest of all things is to be afraid; and, teaching himself that, forget it forever, leaving no room in his workshop for anything but the old verities and truths of the heart, the old universal truths lacking which any story is ephemeral and doomed, love and honor and pity and pride and compassion and sacrifice. Until he does so he labors under a curse. He writes not of love but of lust, of defeat in which nobody loses anything of value, of victories without hope and worst of all without pity, or compassion. He writes not of the heart but of the glands. Until he relearns these things he will write as though he stood among and watched the end of man. I decline to accept the end of man. It is easy enough to say that man is immortal simply because he will endure; that when the last ding-dong of doom has changed and faded from the last worthless rock hanging tideless in the last red and dying evening, that even then there will still be one more sound: that of his puny inexhaustible voice, still talking. I refuse to accept this. I believe that man will not merely endure: he will prevail. He is immortal, not because he alone among creatures has an inexhaustible voice, but because he has a soul, a spirit capable of compassion and sacrifice and endurance. The poet’s, the writer’s duty is to write about these things. It is his privilege to help man endure by lifting his heart, by reminding him of the courage and honor and hope and pride and compassion and pity and sacrifice which have been the glory of his past. The poet’s voice need not merely be the record of man, it can be one of the props, the pillars to help him endure and prevail.

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