某溶液中可能含有Na⁺、K⁺、Mg²⁺、I^—、SO₃^2—、SO₄^2—等离子中的全部或其中的几种。现分别进行以下实验操作：

①用洁净的铂丝蘸取溶液在无色火焰上灼烧，焰色呈黄色；②取原溶液，滴加少量溴水，振荡后溶液仍为无色。③取原溶液，加入盐酸酸化的Ba(NO₃)₂溶液后，产生白色沉淀。

(1)原溶液中一定存在的离子是     ，一定不存在的离子是          。

(2)上述①~③,的操作中，   是错误的，应改为       ，以便确定       离子的存在。

(3)为确定             离子是否存在，应补充的实验是①                            

②                                                                         。

In junior high school, one of my classmates, Ethan, was addicted to TV. This boy simply knew everything about such pop shows as Who’s the Boss?

Then one day Ethan’s mother made an offer in order to draw him back to his school subjects. She promised that she would give him $200 if he could go a full month without watching any TV. None of us thought Ethan could do it, but he did quite well. His mom paid him $200. He went out and bought a TV, the biggest he could find.

In recent years, hundreds of schools have carried out experiments with paying kids with each for showing up or getting good grades. All school kids admire this trend. But it upsets adults. Teachers say that we are rewarding kids for doing what they should be doing of their own will. Psychologists warn that money can actually make kids perform worse by making the act of learning cheap. The debate has become a typical battle over why our kids are not learning at the rate they should he despite decades of reforms and budget increases.

[写作内容] 1. 以约30词概括上文的主要内容。

2. 以约120词对用金钱鼓励孩子学习的现象进行议论，内容包括：

(1)你对用金钱鼓励孩子学习的看法;

(2)你的父母(或其他亲人)是如何鼓励你学习的；

(3)你认为怎样才能更好地鼓励孩子学习。

[写作要求]

1. 可以使用实例或其它论述方法支持你的论点，也可以参照阅读材料的内容，但不得直接引用原文中的句子；

2. 标题自定。

3. 作文中不能出现真实姓名和学校名称。

[评分标准]概括准确，语言规范，内容合适，篇章连贯。