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限一词;

2）只允许修改10处，多者（从第11处起）不计分。

    One day, in my way to school, I noticed two anxious foreigners was surrounded by a group of people. I stopped and found that they were tourist from Canada who carelessly left a very importantly wallet in a taxi. So I take them to the nearest police station. With help of the policemen, we got in touch the taxi company. We were telling that the wallet had just been found. And two passports, flight tickets, or some money were still inside it. Finally the two Canadians got our wallet back. They thanked for me and left.

在一定区城内，生物与环境所形成的统一的整体叫做生态系统．下列有关说法错误的（　　）

把一个圆分割成三个扇形，它们圆心角的度数比为1：2：3，求最大的扇形的圆心角的度数．