The company was encouraging people to _____.
The original idea of viral marketing was very low _____ .
An American company paid people _____ to allow advertisements onto their computer screen.
Many listeners are concerned about _____ .
Good examples of viral marketing are _____ providers like Hotmail and Yahoo.
The difference between viral marketing and spam depends on providing _____ .
Another example of viral marketing is that of _____ sent to your PC.