脊髓震荡是指
A．脊髓受压
B．脊髓挫伤
C．脊髓裂伤
D．脊髓血运障碍
E．脊髓暂时性功能抑制
参考答案：E
_____ scores of times , but he still couldn’t understand it ．[ ]
A．Having explained
B．Having been explained
C．Though it was explained
D．It was explained
风险因素识别在审视项目时，会寻找可能导致项目( )的因素。
A．限制
B．阻挠
C．可行
D．不可行
