1211和1301卤代烷管网灭火系统所保护的单个防护区的面积不宜大于()m2。
A、100
B、200
C、300
D、500
参考答案:D
The law of diminishing returns states that for a given production process, as more and more of a resource (such as labor) are added, holding the quantities of other resources fixed:()
A. cost declines at an increasing rate.
B. cost declines at a decreasing rate.
C. output increases at a decreasing rate.