可导致左心室容量负荷过重的因素是（）
A.肺动脉瓣狭窄
B.主动脉瓣狭窄
C.肺动脉瓣关闭不全
D.主动脉瓣关闭不全
E.心肌梗死
参考答案：D
读一读，猜一猜。
They are twin brothers (孪生兄弟). One is on the right and one is on the left. But they have never
seen each other (从未见过对方).
What are they? They are ______________.
在CT轴位像上，主肺动脉的直径不应大于（）
A.2cm
B.2.5cm
C.3cm
D.3.5cm
E.4cm
