Many lifestyle patterns do such        great harm to health that they actually speed up ______weakening of the human body.

A．a; /

B．/; the

C．a; the

D．/; /

（）用于金属（钢板、铝板）结构件、外部面板的分割。

A、气动往复式切割锯

B、气动磨削工具

C、气动剪

D、气动扳手