下列哪项检查是确诊脊髓空洞症的首选方法（）
A.脑脊液检查
B.X线检查
C.延迟脊髓CT扫描
D.脊髓MRI
E.脊髓造影
参考答案：D
Bad weather prevented the work ____ in time. [ ]
A. completed
B. from completing
C. to be completed
D. being completed
当被测介质低于80℃及2MPa时，安装压力表宜选用（）密封垫片。
A.铝
B.铜
C.橡皮
D.铅
