题目

人类的生产、生活都离不开水。兴趣课上同学们分组研究水的净化及组成（装置如下图）。  （1）一组同学用自制简易净水器（图②所示）净化河水，其中活性炭的作用是  。 （2）实验③中通电一段时间后，试管b中的气体是  （填写化学式），反应的化学方程式为    。 （3）从微观角度分析，实验①和③两个变化中最本质的区别是   。 （4）2 mol水中约有   个水分子。 任务型阅读：       Helen Keller lived in the USA. She was a great woman.       When Helen was a baby, she got very ill. After many weeks, the doctor said, "She is better, but now she can't see and she can't hear." Her mother and father were very sad.       After a few years, things got worse (更糟糕). There was no way for Helen to speak to other people. She heard nothing. She saw nothing. She didn't understand anything.       Then one day a teacher came to live with Helen and her family. The teacher helped Helen learn about words.Helen was a very bright girl and soon she learnt to spell her first word. When she was older, she went to college(大学).       Helen was very famous (著名的). She helped many blind (盲) and deaf (聋) people.       阅读短文，根据短文内容填写表格，每空一词。 Where was Helen Kellerfrom? She was from 1._________. When did she got ill? When she was a 2.__________. Who 3._______ Helen Keller her first word? Her teacher did. Why was she famous? Because she learnt to read and 4.________ and helpedmany blind and deaf people in the world. Helen Keller was blind and deaf, but she was very 5._________.