Every time you go to the grocery store, you try to wait in the shortest line. But the lines always seem to be roughly the same length. Why（）
A. The cashiers work at the same speed
B. The cashiers do not have an incentive to work faster
C. Random chance equalizes the length of the lines
D. Other people are trying to choose the shortest line too
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A rational person（）
A. undertakes activities until the net benefits become less than zero
B. makes choices based on total benefits and total costs
C. considers the financial benefits and financial costs of making a choice
D. makes choices based on added benefits and added costs
Moe has a big exam tomorrow. He considered studying this evening, but decided to hang out with Curly instead. If neither activity involves any explicit costs, and Moe always chooses rationally, it mus
A. Moe gets more benefit from spending time with Curly than from studying
B. Moe gets less benefit from spending time with Curly than from studying
C. the opportunity cost of studying is less than the value Moe gets from spending time with Curly
D. the opportunity cost of studying is greater than the value Moe gets from spending time with Curly
Positive economic principles are those that（）
A. indicate how people should behave
B. are always correct
C. are influenced by political ideology
D. predict how people will behave
Normative economic principles are concerned with how people_make decisions while positive economic principles are concerned with how people_make decisions（）
A. in power; in ordinary life
B. do; should
C. should; do
D. in ordinary life; in power
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