在一个不透明的盒子中，红色、白色、黑色的球共有40个，除颜色外其他完全相同，老师在课堂上组织同学通过多次试验后发现其中摸到红色、白色的频率基本稳定在45%和15%，则盒子中黑色球的个数可能是（　　）.

请根据提示和所学知识写出相对应的人物或名词。

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：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，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。

    I was sitting at my favorite table in a restaurant on last Sunday waiting for the food I had ordered to arrive. I suddenly found that Lin Ling, one of my classmate, worked as a waitress there. Honest speaking, it was great surprise for me to find her working there. As far as I know, she's from a richer family. What made her work there? I walked up to her but asked her the reason. When asking, she said, “I just want to earn some pocket money so that we can help some children in poor areas go back to school.” How a good girl! I should learn from her.

解方程：（y﹣1）²+3（y﹣1）=0．

合作精神根植于本民族文化之中，是民族进步的灵魂，是国家兴旺发达的不竭动力。（   ）