He________sleep，although he tried to，when he got on such a hunt for an idea until he had caught it.    

—Did you visit the museum last week? —No, we _____, but we spent too much time shopping.

—Have you decided when to leave for Australia?—Not yet. We _________ set off at the end of this month.

---My house is very near a busy street.  ---It ________ be very quiet.  

---Is Mr Hu in the reading room?---No, he _______be there. He has gone to Tianjin.