男性患者，53岁，3天前流涕、咳嗽，未诊治。2天前两下肢无力逐渐加重，两上肢亦无力。既往：无高血压及糖尿病病史。查体：四肢肌力3级，腱反射消失，颈5以下痛觉消失，无病理征，脑脊液正常。诊断时最应与以下哪些疾病相鉴别（）

A.周期性瘫痪

B.急性脊髓炎

C.急性脊髓灰质炎

D.基底动脉脑血栓形成

E.急性感染性脱髓鞘性多发性神经病

An inert gas system is designed to reduce the possibility of tank explosions by（）.

A.eliminating sparks and fire in the vicinity of cargo tanks

B.removing all hydrocarbon gases from the cargo tanks

C.blanketing cargo tanks with inert foam

D.reducing the oxygen concentration below levels necessary for combustion