地铁事故灾难应急处置实行（）负责制，城市人民政府是处置事故灾难的主体，要承担处置的首要责任。
参考答案：属地
首次通过法显像，右房显影后，左房左室立即显影，是由于（）。
A.右房至左房分流
B.左房至右房分流
C.三尖瓣反流
D.肺动脉瓣反流
E.主动脉瓣反流
China has produced this year as it did in 1996.
A．as much steel twice
B．as twice much steel
C．twice steel as much
D．twice as much steel
