All of us find ________ necessary to take exercise every day. 

---How many children have you got ? ---Two , _______ of them are studying in the university.

The number of the classes in our school is __________ than__________ of any other school in Nanjing．

The weather in Guangzhou is hotter than_____ in Harbin.

        of four buses will take you to the station . We can take        of them .