脉冲式金属探测门的工作原理是设备发生的一连串的脉冲信号产生一个时变磁场，该磁场对探测

右图是膝关节纵剖面图，填出图中各序号所代表的结构名称：

①             ②         

③             ④         

Day by day, the UN officials are       discussing about Iraq issue. But they wonder how to deal with it.

A．interested in

B．busy with

C．excited at

D．fed up with

民法院审理行政案件，依法实行（）制度。

A、合议

B、回避

C、公开审判

D、两审终审

To make the city look more beautiful, a lot of old houses along the street have been _____.

A．brought down

B．put down

C．turned down

D．pulled down

下列导致催化剂失活的原因中，能被完全再生的是（）。

A、热老化

B、水热老化

C、硫沉积

D、硫酸盐化