组成坐骨神经的神经根纤维为（）
A.L1～L2
B.L4～L5
C.L1～S2
D.L4～S3
E.S1～S5
参考答案：D
--- Did you hear that Malaysia Airline Flight MH307 disappeared off the coast of Australia
--- ______ bad news it is!
A．How
B．How a
C．What
D．What a
为什么靠近导线的绝缘子劣化率高？
