【题目】_____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
在线课程【答案】C
【解析】
试题考查现在分词的完成式。句意：已经排队等了半个小时了，汤姆突然意识到他把钱包落家里了。句子的主语Tom和动词wait之间是主谓关系，因此要用现在分词。故选C。