题目

已知为上的奇函数，且当时，.则当时，____________. 答案：【答案】【解析】当时，,将代入，结合奇函数的性质，即可求出当时，函数的解析式.当时，所以因为是奇函数所以故本题正确答案为4．假定你是李华，你的英国网友Anna在她学校举办的一次作文比赛中荣获一等奖，你写信向她表示祝贺，并在信中谈及自己在英语写作上存在的困难，希望得到她的帮助．注意：1．词数100左右，开头和结尾已给出，不计入总词数；2．可以适当增加细节，以使行文连贯；3．文中不能出现真实姓名和具体学校信息．Dear Anna，I am very glad to learn thatyou have won the first prize in your school's English writing contest．And I am writing to offer my warmest congratulations on your excellent performance．It's a real encouragement to me to see your efforts rewarded．How I admire your writing skills!I have been learning English for several years and I have little trouble in listening，speaking and writing．However，I find it hard to write a good composition．Although I've put a lot of efforts into it，I just can't find a way out．I feel stressed out．I would appreciate it if you could give me some specific advice on it．Looking forward to your early reply．Yours，Li Hua．