With the continuous development and iteration of telecommunication technology, the users' requirements of the quality and service have increased dogmatically. In order to meet the diverse and personalized consumer demands, virtual network operators came into being. In 2013, China officially...

The last century's industrial and technological development has led to the growth of environmental problems such as global warming, climate changes, water, air, and ground pollution. The awareness of modern consumers about these issues is growing, and companies respond by using "green marketing"...