I have authorized him to act for me while I am away.

我已授权他在我外出时代理我的职务。

You could get them under the Trade Descriptions Act for that!

你可以根据《商品说明法》将他们绳之以法。

I give you full power to act for me.

全权代我处理。

He authorized me to act for him while he is abroad.

他授权我在他出国期间代行他的职务。

My parents did this magic act for five years.

我父母表演这套把戏长达五年之久。