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.