---______ visited the Shanghai World Expo is sure to tell you the place is worthy ______ twice.
---You can say that again.
---How long can I ___ this library book?
---Two weeks.
---The problem wasn’t difficult for him,was it?
---No,it wasn’t.He a more difficult one.
--- May I smoke here?
--- If you____, that's the smoking section over there.
---Why? Where is my cellphone?
---Dear me! You _______ it in the taxi!
---Oh, I failed again
---Don’t lose heart. One more effort, ______ you will succeed.
--- ______ I come to London alone?
--- Don’t worry, I ______ be meeting you at the airport.
---Do you know the most ancient city in China ─ Xi’an well?
---No, this is the first time I ___________ here.
---It is around 100 years, known to us all, ______ the first modern Olympic Games was held.
---It really is. But were ______ ?