房性期前收缩药物治疗首选（）
A.β-受体阻滞剂
B.普罗帕酮
C.胺碘酮
D.洋地黄
E.利多卡因
参考答案：A
Thomas, please be quiet. The others _____ hear very well. [ ]
A. can't
B. mustn't
C. shouldn't
D. needn't
浅池理论
