In a market economy, what is true of all trade? it is expensive. it is voluntary. it is ordered by the government. it is forced by the seller.

In a market economy all trade is a voluntary exchange between buyers and sellers. It is not ordered by the government, forced by the seller, but it can be potentially expensive for the consumer. 

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  the domino theory states that  if one country in a region came under the influence of communism, then the surrounding countries would follow in a  domino  effect.