It’s the third time that Li Ming has been to Xi’an , _______?
When I first arrived ________San Francisco,I had a difficult time ________certain aspects of the American way of doing things.
After the long journey, the three of them went back home, _________.
— Are you going to the football game? — No, the tickets are ______expensive for me.
You may use the room as you like ____ you clean it up afterwards.
— I saw a lovely alien(外星人) near the New Bridge Airport last week? — _______ There is no such kind of creature at all.