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。

    Mr. Johnson is a hardworking teacher. Every day, he spends too much time with his work. With little sleep and hardly any break, so he works from morning till night. Hard work have made him very ill. “He has ruined his healthy. We are worried about him.” That is which other teachers say. Yesterday afternoon. I paid visit to Mr. Johnson. I was eager to see him, but outside her room I stopped. I had to calm myself down. Quietly I step into the room. I saw him lying in bed, looking at some of the picture we had taken together. I understood that he missed us just as many as we missed him.

①朝鲜爆发内战

②美国出兵侵略朝鲜

③美国侵略军严重威胁中国安全

④朝鲜政府请求中国出兵援助

该社团将该校区在2016年100天的空气质量指数监测数据作为样本，绘制的频率分布直方图如图，把该直方图所得频率估计为概率．

（Ⅰ）请估算2017年（以365天计算）全年空气质量优良的天数（未满一天按一天计算）；

（Ⅱ）该校2017年6月7、8、9日将作为高考考场，若这三天中某天出现5级重度污染，需要净化空气费用10000元，出现6级严重污染，需要净化空气费用20000元，记这三天净化空气总费用为X元，求X的分布列及数学期望．

如图，OE为∠AOD的平分线，∠COD=$\frac{1}{4}$∠EOC，∠COD=15°，

求：①∠EOC的大小；  ②∠AOD的大小．