为什么肱骨外科颈骨折容易损伤腋神经?
参考答案：
因为腋神经绕肱骨外科颈至三角肌深面，比较贴紧骨面，所以肱骨外科颈骨折时易损伤腋神经。
26.24与13.6的和减去它们的差得多少？
Which of the following is least relevant when explaining why monopoly firms can earn positive economic profits over the long term（）
A. The ability to use price discrimination.
B. The existence of economies of scale.
C. Control over production input resources.
