已知 Cu₂S+2Cu₂O $\underset{\_}{\underset{\_}{△}}$  6Cu+SO₂↑，下列说法正确的是（   ）

下列属于化学变化的是（   ）

注意：1）.每处错误及其修改均仅限一词；
2）.只允许修改10处,多者（从第11处起）不计分。
    More and more foreigners like to come to China. Last Friday our school was invited a foreign teacher in our city give a class to the students of Senior Grade Two. We found his class interested. I learned a lot from him. The teacher had a free talk to us with easy English . He spoke slow so that we could understand him well. Sometimes he repeated what we don't understand. My classmates were all active in the class. To his joy, I understood everything the teacher said. And I was able to ask question in English. This class encouraged me very much. I'm sure that until we keep on practising, it will be easy for us to learn speaking English well.

某实验室的废液中，可能含有FeCl₃、NaCl、Na₂SO₄、Ba(NO₃)₂中的一种或多种。某同学取该废液样品观察为无色溶液，向其中滴加BaCl₂溶液产生白色沉淀，继续加稀硝酸无明显现象。根据以上实验现象分析，下列推断正确的是

据报道，由杭州学军中学等 3 所高中的部分学生参与撰写的两份“模拟提案”一一《关于 急救设施和急救教育的推广普及的提案》和《关于完善现有校园欺凌预防和处理体系的提 案》，交由全国政协委员提交至 2017 年 3 月 3 日开幕的全国政协十二届五次会议。这体现了中学生（  ）

①参加民主管理，直接行使基本政治权利    ②有序政治参与，提升社会责任意识

③履行政治义务，维护国家利益与荣誉      ④参与社会管理，体验协商民主的价值