"Oprah Winfrey praises L'Occitane soap on her TV show."

How can you graphically show the impact of this event on the L'Occitane soap market?

"High gas prices have reduced the sale of large gas-guzzling vehicles."

How can you graphically show the impact of this event on the truck market?

Suppose the price of beef drops, all other things equal. What is going to happen to the milk market as a result of this event?

Some public goods can be funded by advertisement instead of taxation.

Any public good can potentially be converted to a private good.

Most club goods are provided by the government.

When a new edition of a textbook is published, you can no longer resell the old edition. This is a way of converting a non-excludable good to an excludable good.