控制疫情蔓延最有效的措施是
A．隔离伤寒患者B．停止供水C．对饮用水迅速采取氯化消毒D．迅速切断污染源E．加强饮用水的净化
参考答案：D
_____, the players began the game.
A．Having taken our seats
B．Our taking seats
C．We having taken the seats
D．Us having taken the seats
有关早期食管癌的X线表现错误的是
A．局限性粘膜皱壁增粗和断裂
B．局限性管壁僵硬
C．小龛影
D．管腔狭窄
E．梗阻
