下列实验操作正确的是[ ]
A.
B.
C.
D.
答案:B
Great changes ______ in China in the past 20 years.
[ ]
A. took place
B. have taken place
C. were taken place
D. have been taken place
心脏病患者,反复发作心悸不适,来诊当天自觉较好。作心电图P波消失呈锯齿状,频率300次/分,室率75次/分。最可能的诊断是()
A.完全性房室传导阻滞
B.正常心电图
C.房性阵发性心动过速(4:1传导)
D.心房颤动
E.心房扑动(4:1传导)