A．声速变大
B．声速变小
C．声速不变
D．无法确定
答案：A
Now there is a danger ________ the ground may fall in under the heavy traffic.
A．whether
B．if
C．X
D．that
下肢外伤后，引起肢体极度外旋的损伤是
A．髋关节后脱位B．股骨转子间骨折C．股骨上段骨折D．股骨颈骨折E．股骨中段骨折
