nothing but =only是固定短语——无所谓指人还是物啊! 例如:There is nothing but bread left.=There is only bread left nobody but不是固定短语应该是除了...以外没有任何人. Nobody but only John was studying in the classroom. 注意有一个短语是 anything but=not at all是高中的一个难点. 例如:It is anything but a car.