The table used to do duty for a hotel desk.这张桌子以前曾充当旅馆服务台。Let's roll the log up to the fire; it can do duty for a bench.让我们把这圆木滚到炉火边，它能当凳子用呢。Honey can do duty for sugar.蜂蜜可代替白糖用。These nails will have to do duty for the proper pieces.没合适的东西，只好将就用这些钉子了。