After two years’ research, we now have a ________ better understanding of the disease.

A．very

B．far

C．fairly

D．quite

最有助于确诊室性心动过速的心电图表现是

A．P波与QRS波群无固定关系

B．QRS波群形态畸形

C．R-R间期绝对不等

D．T波倒置

E．心室夺获与室性融合波