in the queue for half an hour the old man suddenly realized he had left the cheque in the

问题补充：

in the queue for half an hour，the old man suddenly realized he had left the cheque in the car.

A. Waiting

B. To wait

C. Having waited

D. To have waited

答案：

A. Waiting

B. To wait

C. Having waited

D. To have waited

解析：C考查非谓语动词的用法。根据the old man与wait 之间的关系，应该选择。.一ing形式；再根据句意可知，老人是在主句谓语动词“realized”前就“等了(wait)半个小时“，有明显的先后关系.故要用v一ing形式的完成式。