南方地区农田多为水田，种植水稻为主，也种植小麦、棉花、油菜等．

若x，y满足方程（x+y﹣a）²+|2x-y﹣b|=0，则x-2y=____(用含a、b的代数式表示)．

某同学绘制一幅我国原始居民生活场景的想象图，下列内容与河姆渡原始居民相符的是（    ）

①生活在黄河流域    ②种植水稻    ③住干栏式房子     ④挖井饮水

阅读理解
    Hello, my name is Lina. I'm 10 years old. I'm wearing a red dress. Red is my favourite colour and dresses are my favourite clothes. I like to read books. Fish is my favourite food. Amy is my friend. She is 11 years old. She likes green and her favourite clothes are skirts. She likes to play ping­pong. She likes fish, too. But her favourite food is rice and vegetables. We like to drink juice.

如图所示，AO $\perp$ FD,OD为∠BOC的平分线，OE为射线OB的反向延长线，若∠AOB=40º，求∠EOF、∠COE的度数。