If the production costs fall and the selling price increases, the profit margin will increase.
查看答案
If the production costs rise and the selling price remains the same, the profit margin will increase.
A. 对
B. 错
To achieve economies of scale it is necessary to increase production.
A. 对
B. 错
Economies of scale are achieved because unit costs fall as production increase.
A. 对
B. 错
1.下面哪个不是用例描述（）的内容
A. 用例
B. 参与者
C. 关系
D. 对象
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