下列关于阀型避雷器阀电阻片特性描述正确的是()。
A、正常电压时阀片电阻很小
B、过电压时阀片电阻很大
C、正常电压时阀片电阻很大
D、电压越高阀片电阻越大
参考答案:C
A.They are accurate and easy to pull.
B.Their shooting range is 40 yards.
C.They are usually used indoors.
D.They took 100 years to develop.
患者男性,46岁,既往有高血压病病史,突然出现剧烈胸痛,呈撕裂状,累及胸骨后及上腹部,伴大汗,持续1h不缓解。查体:血压200/110mmHg(26.7/14.7kPa),心率90min,心(一),两肺(一),心电图:左室高电压V4-V6。ST段压低0.1mV。最可能的诊断是
A.冠心病、心绞痛
B.冠心病、心肌梗死
C.肺动脉栓塞
D.气胸
E.主动脉夹层