【对话】
A:It seems you're very busy recently.
A:你最近看起来很忙。
B:Yeah. I have a sudden interest in philosophy and I'm digging into it these days.
B:是的。我突然对哲学十分感兴趣，最近一直在钻研哲学。
do duty for充当
【讲解】
此语指“当……来用”，例如：This is a table that does duty for a hotel desk.(这张桌子用来做旅馆的服务台。）也指“代某人履行职责”，例如：He does gate duty for Mr. Wang.(他代王先生把门。）此语也可以写作do duty as。