增加：在缺词处加一个漏字符号（︿），并在其下面写出该加的词。

删除：把多余的的词用斜线（＼）划掉。

修改：在错的词下面划一横线，并在该词下面写出修改后的词。

注意：1)每处错误及其修改均仅限一词。

2)只允许修改10处，多者（从第11处起）不计分。

    Today we had a chemistry test. I found the test difficulty, but I tried hardly to do it. Suddenly, my best friend Mary asking me to let her to copy my answers. After think for some time, I let her copy my answers. But after the test, all of us were called to the teacher’s office. The teacher was angry because we had same answers in the tests. We were warned not to cheat again so she would need to see our parents. I was very upset. I was just helping a friend. Why does she punish me?

Ⅰ：在用KMnO₄酸性溶液处理Cu₂S和CuS的混合物时，发生的反应如下：

①MnO₄^﹣+Cu₂S+H⁺→Cu²⁺+SO₂↑+Mn²⁺+H₂O（未配平）

②MnO₄^﹣+CuS+H⁺→Cu²⁺+SO₂↑+Mn²⁺+H₂O（未配平）

一辆小车，分期付款要比定价多付10%，一次性付款能打九五折．小强的爸爸算了一下，两种付款方式的差价是15000元．这辆车的定价是____元．

注意：1).词数100左右；

2).可以适当增加细节，以使行文连贯。