2016-2017学年 人教版 选修6 unit4 Global warming learning about language 课件 (5)
2016-2017学年 人教版 选修6 unit4 Global warming  learning about language 课件 (5)第2页

How did come about?

the snow catastrophe

Global warming was one of the important reasons why such extreme climate like severe storms and heavy snow frequently came about.