公 * * 品（publicgoods）
参考答案：
指每个人消费这种产品不会导致别人对该物品的消费减少，具有非竞争性与非排他性。
Which of the following statements is closest in meaning to the passage you have just heard().
A. There is plenty of grain in the world and people need not to worry about it.
B. The world’s population is estimated to explode from over 6 billion now to 19 billion by 2050.
C. The population increase is mainly in undeveloped countries.
D. World demand for foods is predicted to rise 50% by 2030.
车刀的角度中对切削刀影响最大的因素是车刀的（）。
A.前角
B.主偏角
C.刃倾角
D.后角
