We don’t need a lot of friends _______ they are good.
-- What can trees do _________ us ?--- They can _________ harmful gases and produce oxygen .
--- Next week , we will go to visit your school .--- You are welcome _________ our school and you can go _________ to have a look .
--- Tom is one of _________ students in my class . --- Yes . He usually prefers _________ at home to playing outside .
--- We don’t allow _________ in the library .--- So we had better _________ outside .
-- Shenzhen _________ on the coast .--- Yes . It is _________ the north of Hong Kong .