已知f（x）、g（x）都是奇函数，f（x）＞0的解集是（a²，b），g（x）＞0的解集是（$\frac{a^2}{2}$，$\frac{b}{2}$），$\frac{b}{2}$＞a²，那么f（x）•g（x）＞0的解集是（　　）

Liu Maodan

Twelve years old

China

Dear Xiaohong,

    You are a lovely girl. We are in the same class in the primary school. We always have a great time at school. You are my good friend. You always help me in English. Thank you very much! I will remember you forever. Good luck for the future!

Yours,

Liu Miaodan

1958年，“左”的错误开始泛滥的原因是（　　）

①社会主义建设缺乏经验  ②对国情认识不清  ③中苏关系恶化  ④急于求成

若亡郑而有益于君，____。（《左传•烛之武退秦师》）