—Alice,you are supposed________ part in the party in time. —Sorry,but I had an unexpected visitor. A.to take B.to have taken C.to be taking D.taking
答案:B [由下句可知,上句意:你理应及时参加晚会(但事实上没参加);was/were supposed to do表示“本应该发生但实际未发生的事”,相当于be supposed to have done。]