右心室收缩期负荷加重最显著的是（）
A.室间隔缺损
B.房间隔缺损
C.动脉导管未闭
D.肺动脉狭窄
E.法洛四联症
参考答案：D
The Coordinator Surface Search in a SAR situation should display by day（）.
A.the code flags FR
B.a black ball over a black diamond shape
C.code flag Quebec over a black ball
D.two black diamond shapes in a vertical line
简述离心水泵的汽蚀现象？汽蚀有哪些危害？
