Why do global hubs develop?全球中心为什么要发展?

Why do global hubs develop?全球中心为什么要发展?
Why do global hubs develop?
全球中心为什么要发展?

Why do global hubs develop?全球中心为什么要发展?
Background Information:Earth DayApril 22 is Earth Day,our country this year to determine the theme of "treat the earth,protect the environment."Earth Day originated in the U.S..In 1969,Democratic Senator Gaylord Nelson proposed the park in the U.S.schools held workshops on environmental issues,and the following year on April 22 as "Earth Day." Then 25-year-old Harvard Law School student Dennis will soon be the proposal throughout the United States into a large-scale community-based activities,specific ideas,and get enthusiastic support of many young students.April 22,1970,the United States for the first time held a massive "Earth Day",around 2,000 people participated,the United States since World War II,was hailed as the largest social activities.April 22,1990,more than 140 countries around the world,200 million people around the same time held a variety of promotional activities,the theme is how to improve the overall global environment.The event made people more clearly recognize,as the global industry continues to develop,ozone layer destruction,and the resulting global climate change,is becoming a direct threat to the global problem of human existence.The activities of the United Nations approval,then,every year on April 22 was identified as the "World Earth Day."Currently,the more prominent environmental issues,soil erosion,desertification,pollution of freshwater resources.According to UN figures released by the 20th century,the world's forest area 90 at an average annual rate of 2.4% reduction in the past 10 years,the world's total forest area of the disappearance of 94 million hectares.At present nearly half the land surface and more than one billion people affected by desertification.Pollution in the atmosphere,from 1965 t