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.

烟光、日影、露气，皆浮动于疏枝密叶之间。

人体出现组织水肿的原因可能是（　　）

①血浆中蛋白质含量过少   ②血液中尿素含量过高   ③血糖含量过高  ④淋巴循环受阻．

黄土高原生态系统十分脆弱，主要表现在（　　）

①抵御自然灾害能力较低  ②水土流失已得到有效控制

③人地矛盾有所缓解      ④环境遭到破坏后恢复困难．