Question

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

1. A.
   To wait
2. B.
   Have waited
3. C.
   Having waited
4. D.
   To have waited

Answer 1

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。