我国在世界上最早种植的农作物是（   ）

①小麦 ②粟 ③水稻 ④玉米

    Ann is my classmate. She comes from New York, and she lives in Shanghai with her parents now. Every morning, she goes to KFC to have breakfast. Sometimes she buys a hamburger for me. She can't speak Chinese well. In the evening, her father often helps her with it. He's a teacher in our school. He can speak Chinese very well.

    Ann thinks the school life(生活)in China is very interesting. Ann likes reading Chinese books because she wants to know more about China. She tries(努力)to talk with her Chinese friends in Chinese. She hopes to speak Chinese well. She is very happy to live in China. She loves people here.

化简：（1+$\frac{1}{x}$）÷$\frac{x^2-1}{x}$的结果为（　　）

2Na₃PO₄+4CuSO₄+2NH₃•H₂O=Cu₄O（PO₄）₂↓+3Na₂SO₄+（NH₄）₂SO₄+H₂O

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