记cn=(一1)n次方bn+an，求数列cn的前2n项和s2n

如何背英语单词?孩子单词老师记不住,如何是好?对不起,不是老师,“老是” 无老师镇魂单词包括所有的词汇题吗?是背完了就不会错词汇题吗? 英语翻译1.Among civilized people it was once thought that ginger root by some magical power could improve the memory 英语翻译How surprised the people who thought tomatoes poisonous would be if they could know that million of pounds of tomatoes were supplied to soldiers overseas during World War II? 英语翻译4.But no one has been able to prove that fish is any better for the brain than many other kinds of food 英语翻译5.As a matter of fact,milk always meets in the stomach a digestive juice which curdles it; the curdling of the milk is the first step in its digestion 英语翻译6.It is just as foolish to say that one should never eat meat and potatoes together as it is to say that one should never eat bread or drink milk. ,"Good medicine but taste bitter will heal one's illness 三月的第四天七点五十二分三十五秒英语翻译.不要有数字!急 there was always rain in my life Always In The Rain 歌词 But in my city,it __(Rain)a lot in summer.速度啊~~ 怎么判断一种病是在常染色体上还是在性染色体上? 在做生物题时总是头脑发热 尤其是判断一种病是常染色体遗传还是伴性遗传 请细致的讲一下 十分感谢我是一个高中生 有时很腼腆 不敢问老师 我需要知识 如能帮我 感激不尽 此题中,甲病是常染色体这个是怎么判断出来的? 我的太阳花焉焉的,不知怎么了,有什么办法吗?如题 我的太阳能花的叶子不动是怎么回事,叶找不到开关.该怎么才能让叶子动. 为什么彩虹是弯的而不是直的 你是我的太阳,而我不是你的向日葵.有什么内含. 彩虹是怎样形成的?为什么彩虹是弯的? get与gain的区别 一个人必须具备的八种美德是什么? achive ,gain和reach的区别 attain achieve acquire有什么区别（在用于经过长时间努力时)after working for the firm for ten years,he finally _ the rank of deputy director为什么不能填后两个呢 attain和acquire都翻译为获得时的区别 如何能最快记住单词并不易忘 怎么样单词记得快如何才能让初学者快速记单词 我忘的单词比记得单词多,怎么办? attain 和obtain的区别最好有可以辨析的具体的例子 attain obtain achieve的区别 obtain和attain有什么区别?都是获得,有什么区别?举出例句 You can't be too careful为什么表示“应该小心”的意思呢?You can't be too careful这句话应该是表示否定的,为什么表示“应该小心”的意思呢?