in the queue for half an hour Tom suddenly realized that he had left his wallet at home.

问题补充：

in the queue for half an hour, Tom suddenly realized that he had left his wallet at home.

A. To wait

B. Having waited

C. Have waited

D. To have waited

答案：

A. To wait

(答案→)B. Having waited

C. Have waited

D. To have waited

解析：

试题解析：考查考查非谓语动词做状语。动词与逻辑意义的主语是主动关系，同时动作发生在主句之前，所以用分词的完成时。句意： Tom 排队等了半个小时后，他突然意识到把钱包落家里了。