hardly.when是一个句型,意思是“一……就……”,不是说什么“坐不住了”.这句话的意思是,我们一坐下来她就给我们拿出了一盘盘食物.（楼主打错字了,是brought,不是bought.另外一点要注意的是,如果hardly放在句首则必须局部倒装,如Hardly had we sat down when she brought plates of food.