科学兴趣小组在调查一化工厂时，发现有个车间排出的废水澄清透明，呈黄色．为测定该废水中所含的物质，他们进行如下实验（假设能发生的反应均恰好完全反应）：

①用pH试纸测试，测得pH为2．

②取一定量废水溶液，加入Ba（NO₃）₂溶液，无现象．

③另取一定量废水溶液，加入AgNO₃溶液后，过滤，得到白色沉淀A和滤液．

④向滤液中加入NaOH溶液，得到红褐色沉淀B．

由此可知：该废水溶液呈____性；所得的红褐色沉淀B为____；废水溶液中肯定含有的盐是____．

如图所示，在电磁铁的上方用弹簧悬挂着一条形铁棒，开关S闭合后，当滑片P从a端向b端滑动过程中，会出现的现象是（ ）

“徒法不足以自行”，建设法治社会，需要公民对法治社会具有发自内心的认同和尊崇，做法治社会的合法、合格公民。法治社会的合法、合格公民表现为（    ）

①公民采取合法方式行使质询权

②公民坚持理性表达、有序参与

③公民的民主意识和法制意识不断增强

④公民通过人大代表联系群众制度参与民主决策

    My mom works on Saturdays, so every Saturday my aunt, Jenny, takes me somewhere interesting. For example, once she took me to the sea museum, and then she made me do a project (专题研究) about my favorite 1 .

    Last Saturday, Jenny took me to an old people's home. She was a volunteer (志愿者) there, so she 2 went there in her free time. There were a lot of old People there. Jenny introduced (介绍) 3 to some of them. Then she asked me if I would like to read the newspaper to them. I was glad to do that. I read 4 so they could hear me. They said my reading was excellent. I felt really 5 .

    Later, Jenny and I had lunch with them. I sat at a table with one man and two women. During lunch, they told me stories 6 their lives. The man had been a guide. The two women were from other 7  Mrs. Wang came from China, and Mrs. Guleed was from South Africa. They 8 their lives in their hometowns. It sounded different.

    After lunch, Jenny 9 the piano. Some of the people sang along to the music. The people there were very kind to me. I liked them so much that I began to 10 them as Soon as I got home.