有关颅底骨折，下列哪些正确（）
A.多为线形骨折
B.属于开放性骨折
C.X线片能明确诊断
D.有意识障碍
E.常并发脑神经损伤
参考答案：A, B, E
An analyst does research about market supply curve. Which of the following statements is most accurate（）
A. The market supply curve is a total cost curve.
B. The market supply curve is the horizontal sum of the individual producer's supply curves above average variable cost curve.
C. The market supply curve is formed by adding the producer surplus of all individual producers.
