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Define production possibility curve

Read the following: (1) liz has become more responsive to her partner's advances since a really beautiful woman moved in next door; (2) unable to accept his desire for other young men, 15-year-old juan immerses himself into his studies; (3) shauntel tells people that her coworker mary dislikes her; though if she were honest, shauntel would realize that it is actually she who dislikes mary; (4) "ben's nasty; he's disgusting," says renee; but renee secretly finds ben attractive. describe the defense mechanism he or she is using.

What are the most populous and least areas of russia and why are some areas more heavily populated than others