诊断二尖瓣狭窄最常用和可靠的方法是（）
A.心电图
B.心导管检查
C.X线检查
D.超声心动图检查
E.心脏听诊
参考答案：D
如果企业发生破产清算，所有以持续经营为前提的会计程序和方法就不再适用。（）
Continuous sounding of a fog whistle by a vessel is a signal（）.
A.that the vessel is anchored
B.to request the draw span of a bridge to be opened
C.of distress
D.that the vessel is broken down and drifting
