This is the watch for which I am looking . The babies (whom / who / that) the nurse is looking after are very healthy. The babies after whom the nurse is looking are very healthy. 2.若介词放在关系代词前,关系代词指人时只可用 whom,不可用who, that;关系代词指物时只可用 which,不可用that。关系代词是所有格时用whose。 The man with whom you talked just now is my neighbour.