无器质性心脏病的室性期前收缩，若无明显症状，治疗首选（）
A.倍他乐克
B.利多卡因
C.美西律
D.普罗帕酮
E.不必药物治疗
参考答案：E
It's reported that________560,000 visitors from home and abroad visited the Shanghai Expo site over the first three days.[ ]
A. mainly
B. approximately
C. obviously
D. fundamentally
