当胶结绝缘接头的轨缝拉开，工务部门必须及时拧紧接头螺栓和前后各（）m扣件螺栓，并做好更换得准备。
A.30
B.50
C.80
D.100
参考答案：B
Great changes have taken place around the world. Nobody can tell _____ in 20 years.
A．what will it be like
B．how it looked like
C．what it will be like
D．how did it look like
骨折造成的周围神经损伤可由以下哪些因素引起（）。
A.骨折时神经受牵拉
B.骨折端的刺伤
C.骨折端的压迫
D.骨痂包裹
E.肢体迟发性畸形引起的牵拉
