A．An industry with low cost but high output.
B．A field not maintained for the purpose of making a profit.
C．A commodity freely attached by other high-grade goods.
D．A product sold at a low price to draw customers.
A．Carrying a classified advertisement in the Sunday editions.
B．Subtracting certain survey reports.
C．Collecting repays for posts about merchandise.
D．Selling companies sponsored content.
A．Funding models.
B．Cooperative partners.
C．Target groups.
D．Marketing channels.