发动机发生拉缸,原因:活塞环折断而拉伤()。
参考答案:气缸
Which of the following conditions is most likely to exist for a typical production process when average product is at its maximum()
A. Marginal product is increasing.
B. Marginal product is at a minimum.
C. Average variable cost is at a minimum.
请写出三种以上演唱形式及其代表作品。