下列哪些疾病心脏相对浊音界可呈靴形()
A.二尖瓣关闭不全
B.三尖瓣关闭不全
C.主动脉瓣关闭不全
D.肺动脉瓣关闭不全
E.缩窄性心包炎
参考答案:A, C
________ he still paused uncertain, he became aware that the driver was looking closely in from the street at this unusual scene.
A.While
B.As
C.Since
D.Because
使用自动闭塞法行车时,出站信号机不能显示绿色灯光,仅能显示黄色灯光时,办理特快旅客列车通过,行车凭证为出站信号机的黄色灯光并发给司机()。
A、路票
B、调度命令
C、绿色手信号
D、绿色许可证