题目

—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。]既要在一充满空气的瓶子中，将其中的氧气除去．又不增加其他气体的成分．下列物质在瓶中燃烧可达到目的是（ ）A．木炭B．硫磺C．铁丝D．红磷