【分析】从组成上看，NH₄Cl属于铵盐，含有NH₄⁺，与强碱溶液反应会有氨气产生，NaOH溶液和Na₂CO₃溶液中因为含有不同阴离子，所以性质不同，据此可鉴别．

【设计方案并实验】

【反思与评价】小组同学讨论后一致认为小贝的结论不正确，理由是____．

【方法感悟】在检验物质时，要分析物质的组成和____，据此选择加入适当的试剂，最后根据不同现象得出结论．

【问题处理】几天后，小明才发现取完C后忘了及时盖上瓶塞，若要除去其中杂质，可向其中加入适量的____溶液．

下列措施中不属于节约用电的是（　　）

    Jim Green is a student in No. 5 Middle School. He does a part-time 1because he needs some2. He works in a supermarket after3from Monday to Friday and all4on Saturday. He helps people look after their kids and he plays 5kids. He thinks it is great6. After school, he7a bus to the supermarket. He8there at about 4: 30. He works94: 30 to 8: 30. He gets 10 at 9: 30. Jim likes his job very much.

报纸是政策、新闻、广告宣传的重要媒介，下列哪一份是中国创办的最早的报纸（    ）