血管扩张药治疗心衰的药理学根据是（）.
A.降低心排出量
B.扩张动、静脉，降低心脏前后负荷
C.降低血压
D.减慢心率
E.改善冠脉血流
参考答案：B
While building a tunnel through the mountain, ________ .
A．an underground lake was discovered
B．there was an underground lake discovered
C．a lake was discovered underground
D．the workers discovered an underground lake
在上纵隔和后纵隔都可以见到的结构是（）
A、食管
B、迷走神经
C、气管
D、膈神经
E、胸导管
