右心室前负荷增加可见于（）
A．二尖瓣狭窄伴肺动脉高压
B．三尖瓣关闭不全
C．主动脉瓣狭窄
D．主动脉瓣关闭不全
参考答案：B
—Do you like cooking, Sally?
— . Luckily I’ve never had to worry about it.
A．Never mind
B．Not really
C．I don’t agree
D．You said it
列管式废热锅炉为什么会结垢？如何防止？
