People all around the world have been doing as much as they can ________the people in Afghanistan.

A．help　　

B．to help

C．helping　　

D．helped

下面四组中可以用作脚手板的是（）

A．钢脚手板木脚手板竹脚手板；

B．钢脚手板铁脚手板竹脚手板；

C．铁脚手板木脚手板竹脚手板；

D．钢脚手板铁脚手板木脚手板；