肺动脉楔压(PAWP)是()
A.反映左心室平均压
B.反映左心房平均压
C.反映右心室平均压
D.反映右心房平均压
E.反映上、下腔静脉平均压
参考答案:B
We ______ here two hours ago. We ______ here for two hours. [ ]
A. have arrived, have been
B. have come, have been
C. came, have come
D. arrived, have been
电路交换特点: