单项选择题
A. finding out some rare species of fish B. collecting data about local fishing C. encouraging profitable fishing methods D. enjoying the native fishing culture
A. more brisk commercial activities in the cities B. more low-income people living in the suburbs C. higher incidence of tax avoidance by industries D. heavier tax burdens on the remaining citizens
A. recognize where a threat has come from B. compare the benefits of different actions C. weigh merits and demerits of game theory D. escape attacks from powerful predators