下图提示的心电图改变为（）
A.预激综合征
B.左束支传导阻滞
C.房室传导阻滞
D.右束支传导阻滞
E.室内差异传导
参考答案：D
It’s too bad that I failed in the math exam. If only I ______ hard at it!
A．worked
B．had worked
C．has worked
D．would work
sourceofinfection
