16.I would love ________ to the party last night but I had to work extra hours to finish a report.
A. to go
B. to have gone
C. going
D. having gone
17.________ in thought， he almost ran into the car in front of him.
A. Losing
B. Having lost
C. Lost
D. To lose
18.—You were brave enough to raise objections at the meeting.
—Well， now I regret ________ that.
A. to do
B. to be doing
C. to have done
D. having done
19.The missing boys were last seen ________ near the river.
A. playing
B. played
C. play
D. to play
20.The visiting minister expressed his satisfaction with the talks， ________ that he had enjoyed his stay here.
A. having added
B. to add
C. adding
D. added
