题目

人类的TSD病是由于某种酶的合成受到抑制引起的，该酶主要作用于脑细胞中脂类的分解和转化。病人的基因型是aa，下列哪项可以解释Aa型的个体可以像AA型人那样健康生活（    ） A．Aa型的细胞内，基因A可以阻止基因a的转录 B．Aa型的细胞内，基因A诱导基因a发生突变 C．Aa型体内所产生的此种酶已足够催化脂类的正常代谢 D．Aa型体内，脑细胞的脂类分解和转化由另一种酶催化口语运用, 根据所给情景选择最佳答案。1. When your friend wants you to help him, he may say "           ". [     ]A. Can I help you? B. Thank you for your help.C. Could you help me? D. You're welcome. 2. If you meet a foreigner in the street, you can talk to him like "           ". [     ]A. Hi! What's your name? B. Could I ask you a question? C. It's fine today, isn't it? D. Did you have the meal? 3. Li Ming asks you "What do you think of the movie?", how can you answer? [     ]A. I don't know.B. Don't ask me.C. I think so. D. I enjoy it a lot. 4. When someone asks you the way to the train station, you should say "           ". [     ]A. Thank you. B. I'm afraid not. C. Sorry, please ask that policeman. D.You're unlucky, I don't know. 5. If someone asks "What rules do you have at home?", you may answer "           ". [     ]A. I often watch TV. B. I'm not allowed to go out on school nights. C. I don't like to stay at home. D. It's a good question.