急性心肌梗死时发生室颤尽快用（）
A.同步直流电复律
B.非同步直流电除颤
C.体外反搏术
D.心室按需型起搏器
E.以上都不宜应用
参考答案：B
—Did the policeman let you in?
—No, ________ I told him who I was. [ ]
A. if
B. as if
C. as though
D. even though
交流电的周期和频率互为倒数。
