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

A.To wait

B.Have waited

C.Having waited

D.To have waited

答案及解析： C

解析：

本题考查非谓语动词作状语。先排除B项，因为B项是谓语动词形式，不可作状语；

A、D两项为不定式形式放在句首时常作目的状语，这显然与本题逻辑上不符。