从所给的四个选项中，选择最合适的一个填在问号处，使之呈现一定的规律性（）
A.选项A
B.选项B
C.选项C
D.选项D
参考答案：B
休克时很少发生不可逆变化的脏器是（）
A.脑
B.肺
C.心脏
D.肝
E.肾
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.
