单选题 ______ in the queue for half an hour, Tom suddenly realized that he had left his wallet at home.
  • A. To wait
  • B. Waiting
  • C. Having waited
  • D. To have waited


【正确答案】 C
【答案解析】此句应该用分词短语的完成形式表示在主句谓语动词之前发生的动作。