步骤：

1. 找物质：氧化/还原剂、氧化/还原产物

2. 算得失：计算变价元素的电子得失数

3. 补酸碱：根据电荷数补上$H^+$或$OH^-$或$H_2O$

4. 查守恒：电子守恒、元素守恒、电荷守恒

注意事项：

1. 不要在酸性环境中生成碱或在碱性环境下生成酸

2. 不要漏掉条件或符号（浓、(g)、气体、沉淀、加热等）

（阅读微技能：辨别字面意义和隐含意义）

Implied meaning is suggested but not directly expressed.

Why do we need to identify implied meaning: If you fail to identify the implied meaning, it may cause misunderstanding. By identifying the implied meaning, you can understand what is not directly expressed so as to understand the purpose and attitude.

How to:

1. Understand the literal meaning.

2. Infer the implied meaning logically with the context(上下文). By topic, synonym, hyponym(下位概念).

（阅读微技能：根据上下文理解新词）

Compare to looking up the new words in a dictionary while we come across new words in reading, using context to understand the new words is better.

How to: Find Clues.

Clues: Includes word clue, sentence clue.

1. Word clue: Synonym(近义词), antonym(反义词), the connection between the words.

2. Sentence clue: To catch sentence clues, we need to find the “sign word“, which may delicate the contrast, examples or explanation.

（阅读微技能：做预测和推断）

Look at the pictures or titles and think about the content before reading.

This helps you to relate what you read to what you already know and to understand the new text.

This needs: Attention and inferences.

Tips:

1. Clues:

   1. Text features: Includes Illustrations, Captions, Photographs, Subtitles, Titles.

   2. Prior(背景) knowledge: Includes the category(文章类别), all the experiences you have with that category.

   3. Comprehension(理解性) questions: Use the comprehension questions to predict.

2. Steps:

   1. Beginning with preparation: To preapre by making predictions.

   2. Check your understanding: After making predictions and reading, you should make inferences about meaning and purpose.

1 常见离子的检验方法

沉淀反应，例如$Cu^{2+}$: $Cu(OH)_2$蓝色沉淀

颜色反应，例如$Fe^{3+}$: 加入$KSCN$溶液变成血红色

2 $Cl^-$的检验方法

先加入稀$HNO_3$酸化，再加入$AgNO_3$溶液，若生成白色沉淀，说明含$Cl^-$

前提：$Cl^-$只能被$Ag^+$沉淀

3 $Fe^{2+}$的检验方法

1. 加入可溶性碱（例如$NaOH$），若生成的沉淀从白色沉淀变为灰绿色沉淀，再变为红褐色沉淀，说明含$Fe^{2+}$

2. 加入$KSCN$溶液，若无明显现象，再加入新制氯水，若溶液变红，说明含$Fe^{2+}$

3. 加入铁氰化钾溶液，若生成蓝色沉淀，说明含$Fe^{2+}$

4 $K^+$的检验方法

焰色反应，火焰呈紫色（记得透过蓝色钴玻璃观察）

5 $NH^+_4$的检验方法

加入$NaOH$溶液，同时加热，若有能使湿润的红色石蕊试纸变蓝的气体产生，说明含$NH^+_4$

前提：$NH^+_4+OH^-=$加热$=NH_3\uparrow+H_2O$