问题

_____ 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

正确答案是：

同类题型

have seen, the focus of medical care in our society has been __________ from curing diseases to preventing diseases—especially in terms of changing our many unhealthy behaviors.

Have you ever ________ to Qingdao There is ______ aquarium at the seaside.

Tom received an invitation from Carrol but he ______.

－Isit OK to take this seat －Sorry_______

Why are you so depressed —I _____ myMP4 player on the bus