世界面积最大的大洋是　____ 　，最小的大洋是　____ 　．

    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.

有一人用一滑轮组分别将1000N和2000N的物体匀速提高相同的高度，动滑轮重200N，绳重及摩擦都不计，则在上述两种情况中（　　）